Explanation / Rationale

a) Is not correct. Quality should be the responsibility of everyone working on the project and not the sole responsibility of the test team
b) Is not correct. First, it is not a benefit if an external test team does not meet delivery deadlines, and second, there is no reason to believe that external test teams will feel they do not have to meet strict delivery deadlines
c) Is not correct. It is bad practice for the test team to work in complete isolation, and we would expect an external test team to be concerned with changing project requirements and communicating well with developers
d) Is correct. Specifications are never perfect, meaning that assumptions will have to be made by the developer. An independent tester is useful in that they can challenge and verify the assumptions and subsequent interpretation made by the developer

Explanation / Rationale

a) Is correct. Checking that the sort function puts the elements of the list or array in ascending order is evaluating the functional correctness of the sort function, which is part of functional testing
b) Is not correct. Assessing whether the sort function meets its non-functional requirement to complete within one second is part of testing its performance efficiency, which is part of non-functional testing
c) Is not correct. Evaluating the ease with which the sort function can be modified from sorting ascending to sorting descending is testing its modifiability, a form of non-functional maintainability testing, which is part of non-functional testing
d) Is not correct. Assessing that the sort function still functions correctly when moved from a 32-bit to a 64-bit architecture is testing its adaptability, a form of portability testing, which is part of non-functional testing

Explanation / Rationale

a) Is not correct. Feedback can improve the test process, but if one only wants to improve future projects, the feedback does not need to come early or frequently
b) Is not correct. Feedback is not used to prioritize requirements
c) Is not correct. The quality of changes can be measured in multiple ways
d) Is correct. Early and frequent feedback allows for the early communication of potential quality problems

Explanation / Rationale

a) Is not correct. Impediments to testing can be high level and business-related, so this is an important piece of information for business stakeholders
b) Is correct. Branch testing is a technical metric used by developers and technical testers. This information is of no interest to business representatives
c) Is not correct. Test progress is project related, so it may be useful for business representatives
d) Is not correct. Risks impact product quality, so it may be useful for business representatives

Explanation / Rationale

a) Is not correct. Exploratory testing uses test charters, not a list of possible defects/failures. Although exploratory testing can incorporate the use of other test techniques, in this case fault attack is the most likely option
b) Is correct. This is a list of possible failures. Fault attacks are a methodical approach to the implementation of error guessing and require the tester to create or acquire a list of possible errors, defects and failures, and to design tests that will identify defects associated with the errors, expose the defects, or cause the failures
c) Is not correct. The tester is using a checklist of items to support their testing. Both error guessing and checklist-based testing use such lists, however, the list here is of possible failures, not test conditions, and so the MOST PROBABLE test technique is fault attack, which focuses on errors, defects and failures
d) Is not correct. BVA is based on an analysis of boundary values of equivalence partitions. The above list does not mention equivalence partitions or their boundaries

Explanation / Rationale

a) Is not correct. In agile software development, deliverables are produced in each iteration, and the frequent delivery of increments necessitates extensive regression testing. Although some (or all) of this regression testing may be automated, the regression testing (automated or not) cannot be replaced by system test automation
b) Is correct. If a sequential development model is used, then early in the lifecycle no code is available for execution, and so during this time static testing (e.g., reviews) is performed. Later in the lifecycle, when code is available for execution, dynamic testing is possible. Note, however, that preparation for dynamic testing will often occur early in any software development lifecycle
c) Is not correct. If an iterative development model, like agile software development, is used, then component tests may well be used for regression testing for each iteration. In which case, there is a strong argument for automating these component tests, which will have to be run frequently, and there is unlikely to be a strong argument for developers performing these component tests manually
d) Is not correct. In most incremental development models, deliverables are produced in each increment, requiring both static and dynamic testing at all test levels for each increment delivered

Explanation / Rationale

a) Is not correct. The testing role is primarily responsible for the technical and engineering aspects of testing, such as test analysis, test design, test implementation, and test execution. Evaluating the test basis for defects and the test object for testability are tasks performed as part of test analysis, so it is likely they are tasks performed by the testing role
b) Is not correct. The testing role is primarily responsible for the technical and engineering aspects of testing, such as test analysis, test design, test implementation, and test execution. Defining the test environment requirements is a task performed as part of test design, so it is likely to be a task performed by the testing role
c) Is not correct. The testing role is primarily responsible for the technical and engineering aspects of testing, such as test analysis, test design, test implementation, and test execution. Assessing the testability of a test object is a task performed as part of test analysis, so it is likely to be a task performed by the testing role
d) Is correct. The test management role primarily involves activities related to test planning, test monitoring and control, and test completion. Thus, creating the test completion report, which is the prime output from the test completion activity, is likely to be a task performed by the test management role

Explanation / Rationale

a) Is not correct. In all types of reviews there is more than one role, even in informal ones
b) Is correct. There are several activities during the formal review process
c) Is not correct. Documentation to be reviewed should be distributed as early as possible
d) Is not correct. Defects found during the review should be reported

Explanation / Rationale

a) Is not correct. A member without a missed deadline can get a discount and a gift T-Shirt after 15 bicycle rentals
b) Is not correct. A member without a missed deadline can get a discount but no gift T-Shirt until they rented a bicycle 15 times
c) Is not correct. Non-members cannot get a discount, even if they did not miss a deadline yet
d) Is correct. No discount as a non-member that has also missed a deadline, but only members can receive a gift T-Shirt. Hence, the action is not correct

Explanation / Rationale

a) Is correct. Obtaining feedback from stakeholders early and often in the software development process can be highly beneficial. It facilitates early communication of potential quality issues, can prevent misunderstandings about requirements, and ensures that any changes in stakeholder requirements are understood and implemented sooner
b) Is not correct. The feedback is from stakeholders, and them providing feedback is unlikely to improve their understanding of their own user requirements
c) Is not correct. Obtaining feedback from stakeholders early and often in the software development process can be highly beneficial. It facilitates early communication of potential quality issues, can prevent misunderstandings about requirements, and ensures that any changes in stakeholder requirements are understood and implemented sooner. However, because changes in requirements can be understood and implemented sooner, it does not mean that unlimited changes to requirements are encouraged
d) Is not correct. The feedback is from stakeholders and does not cover communication to them. Communications to end users could include them being told about which requirements will not be implemented prior to release, but ideally this should not happen at all

Explanation / Rationale

a) Is not correct. The paragraph contains information on test levels and exit criteria, which are part of the test approach
b) Is not correct. The paragraph contains information on test levels and exit criteria, which are part of the test approach
c) Is not correct. The paragraph contains information on test levels and exit criteria, which are part of the test approach
d) Is correct. The paragraph contains information on test levels and exit criteria, which are part of the test approach

Explanation / Rationale

a) Is not correct. DevOps enhances testing in several ways, such as by providing fast feedback on code quality, automated regression testing that minimizes regression risk, and promoting a shift-left approach with high-quality code submission and component tests. This is largely provided through continuous integration, where the developers submit component (unit) tests with their new code, which must pass for the code to be admitted to the build. Therefore, developers do need to complete component testin
b) Is correct. DevOps enhances testing in several ways, such as by providing fast feedback on code quality, automated regression testing that minimizes regression risk, and promoting a shift-left approach with high-quality code submission and component tests
c) Is not correct. DevOps enhances testing in several ways, such as by providing fast feedback on code quality, automated regression testing that minimizes regression risk, and promoting a shift-left approach with high-quality code submission and component tests. Testers do not attempt to treat developers and operations equally by spending more time on release testing, although a shift-right approach to testing (testing in production) may well be used
d) Is not correct. Automated processes like continuous integration/continuous delivery (CI/CD) in DevOps facilitate stable test environments and reduce the need for manual testing, however, there is a risk of overlooking the importance of manual testing, especially from a user's perspective

Explanation / Rationale

a) Is not correct. Usability testing is business facing testing that critiques the product (Q3)
b) Is not correct. Functional testing is business facing testing (Q2)
c) Is not correct. User acceptance testing is business facing testing that critiques the product (Q3)
d) Is correct. Component integration testing is technology facing testing that supports the team (guides the development) (Q1)

Explanation / Rationale

a) Is not correct. Testing quadrants have nothing to do with describing the relationships between test levels
b) Is not correct. Testing quadrants cannot help in assessing any type of coverage
c) Is correct. Testing quadrants allow managers and other stakeholders to understand the relationships between test types, the activities they support (team support or product critique), and the viewpoint they are focused on (business- or technology-facing)
d) Is not correct. Testing quadrants is not a psychological model

Explanation / Rationale

a) Is not correct. Scope creep is an example of a project risk related to technical issues
b) Is correct. Poor architecture is an example of a product risk since it refers to a product characteristic
c) Is not correct. Cost-cutting is an example of a project risk, related to organizational issues
d) Is not correct. Poor tool support is an example of a project risk related to technical issues
e) Is correct. Response time too long is an example of a product risk since it refers to a product characteristic

Explanation / Rationale

a) Is not correct. A lack of usability provided through the user interface can be detected through a review using a suitable checklist, but the lack of usability can also be identified by getting several typical users to dynamically test the user interface and provide feedback on its usability
b) Is correct. A code review can detect code that cannot be reached by any path, however dynamic tests can only exercise reachable code and cannot determine that code cannot be reached without running every possible combination of inputs and input states, which is impractical for real code
c) Is not correct. Poor response times for most of the expected users are difficult to determine without executing the code (i.e., by static testing), so in this situation dynamic testing could find a defect, but static testing is unlikely to find it
d) Is not correct. A review of the code by someone who is aware of the required features could detect that the required features had not been implemented in the code, and dynamic testing could also be used to determine that these required features had not been implemented

Explanation / Rationale

Let us refer to the transitions with E1, …, E5 as in the picture. The variable N denotes the number of elements currently stored. Each “Add” event increases it by 1, and each “Remove” event decreases it by 1. Notice, that when the “Add” event occurs while being in the NOT FULL state, the state changes to FULL only if N=2. If N<2, the system stays in the NOT FULL state. If N=0, no “Remove” action is possible. Similarly, if N=3, no “Add” action is possible.

Test a) can be written as E1, E3, E3, E2, E4 (so covers 4 out of 5 valid transitions, achieving 80% valid transitions coverage).
Test b) is infeasible, because after the first three “Add” actions the system is in the FULL state and there is no valid transition going from FULL triggered by the “Add” event. After the first three transitions only 60% of valid transitions coverage is achieved.
Test c) can be written as E1, E2, E4, E5, E3 (so covers 5 out of 5 valid transitions, achieving 100% valid transitions coverage).
Test d) can be written as E1, E2, E4, E5, E4 (so covers 4 out of 5 valid transitions, achieving 80% valid transitions coverage).

Thus:
a) Is not correct
b) Is not correct
c) Is correct
d) Is not correct

Explanation / Rationale

Considering each of the listed test activities and their tasks:

A. Test analysis - To identify the features that require testing, the test basis is analyzed and defined as test conditions, which are then prioritized along with related risks. During this test analysis, defects in the test basis are typically uncovered, and the test object's testability may also be assessed. (Task 4)
B. Test design - Involves using test conditions to create test cases and other necessary testware, such as test data requirements and test charters for exploratory testing. (Task 1)
C. Test implementation - Test procedures, such as manual and automated test scripts, are created from test cases and may be assembled into test suites. Test procedures are prioritized and arranged in a test execution schedule. (Task 3)
D. Test completion - Occurs at project milestones, such as release, end of iteration or end of test level. Testware is identified and archived or handed to the appropriate teams for reuse, the test environment is shut down, and the test activities are analyzed for lessons learned and future improvements. (Task 2)

Thus:
a) Is not correct
b) Is correct. The CORRECT match is: 1B, 2D, 3C, 4A
c) Is not correct
d) Is not correct

Explanation / Rationale

a) Is not correct. This is the task of the review leader
b) Is correct. This is the task of the management in a formal review
c) Is not correct. This is the task of the moderator
d) Is not correct. This is the task of the scribe

Explanation / Rationale

a) Is not correct. Risk management consists of risk analysis and risk control. Neither of these activities supports the reassembly of the files that made up the release, because these activities deal with risks, not with configuration items
b) Is not correct. Test monitoring is concerned with gathering information about testing. This information is used to assess test progress and to measure whether the test exit criteria or the test tasks associated with the exit criteria are satisfied, such as meeting the targets for coverage of product risks, requirements, or other acceptance criteria. Test control uses the information from test monitoring to provide, in the form of control directives, guidance and the necessary corrective actions to achieve the most effective and efficient testing. None of these activities deal with the management of configuration items
c) Is not correct. The whole-team approach builds on the tester’s skill to work effectively in a team context and to contribute positively to the team goals. So, it focuses on team-related issues, not on configuration items
d) Is correct. Configuration management provides a discipline for identifying, controlling, and tracking work products. Configuration management keeps a record of changed configuration items when a new baseline is created. Using configuration management, it is possible to revert to a previous baseline in order to reproduce previous test results

Explanation / Rationale

There are three equivalence partitions: {..., 10, 11}, {12}, and {13, 14, ...}.
The boundary values are 11, 12 and 13. In the three-point boundary value analysis for each boundary, we need to test the boundary and both its neighbors, so:

• for 11 we test 10, 11, 12

• for 12 we test 11, 12, 13

• for 13 we test 12, 13, 14

Altogether we need to test 10, 11, 12, 13, and 14

Thus:
a) Is not correct
b) Is not correct
c) Is correct
d) Is not correct

Explanation / Rationale

a) Is not correct. The whole-team approach allows any team member with the requisite skills and knowledge to undertake any task, however that does not mean that team members can take on any role at any time. Typically, they only take on roles in which they are competent, and there is no suggestion that every team member can do every role
b) Is not correct. The whole-team approach applies to how a single team (typically in Agile software development) works; it does not cover how multiple teams are supposed to work on larger projects, and it does not suggest that only one ‘whole’ team is needed for a complete project
c) Is not correct. The whole-team approach does not expect every team member to be involved in every important decision. For instance, there is no need for the business representative (i.e. the Product Owner) to be involved in every technical decision that does not affect the business outcome and implementing such an approach would unnecessarily slow down the team’s progress
d) Is correct. By leveraging the diverse skill sets of each team member most effectively, the whole-team approach fosters superior team dynamics, promotes robust communication and collaboration, and generates a team synergy that benefits the entire project

Explanation / Rationale

a) Is not correct. Test environment readiness is a resource availability criterion; hence it belongs to the entry criteria
b) Is not correct. This is a resource availability criterion; hence it belongs to the entry criteria
c) Is correct. Estimated defect density is a measure of diligence; hence it belongs to the exit criteria.
d) Is not correct. Requirements translated into a given format result in testable requirements; hence it belongs to the entry criteria
e) Is correct. Automation of regression tests is a completion criterion; hence it belongs to the exit criteria

Explanation / Rationale

a) Is not correct. Although it is true that the tester can implement and execute detailed test cases based on the checklist, it does not explain how this would result in increased coverage
b) Is not correct. Checklist items should not be automated. But even if they are, the automated test scripts always execute the tests in the same way, which usually does not result in increased coverage
c) Is not correct. It is true that each checklist item should be tested separately and independently. But this impacts the test execution order and does not impact the achieved coverage, and so does not result in increased coverage
d) Is correct. If the checklists are high-level, some variability in the actual testing is likely to occur, resulting in potentially greater coverage but less repeatability. If two testers follow a checklist of high-level items, each of them may use different test data, test steps, etc. This way, one tester will probably cover some areas not covered by the other tester and this will result in increased coverage

Explanation / Rationale

a) Is not correct. Test execution and coverage tools facilitate the automated execution of test cases and the measurement of the coverage achieved by running those test cases. However, these tools do not help with the organization of defects and configuration management
b) Is not correct. Test design and implementation tools facilitate the generation of test cases, test data and test procedures, but they do not help with the organization of defects and configuration management
c) Is not correct. Defect management tools are used to manage defects but are not testing tools and are not used to organize test cases or configuration management
d) Is correct. Test management tools increase the test process efficiency by facilitating the management of the software development lifecycle (SDLC), requirements, tests, defects, and configuration management

Explanation / Rationale

a) Is not correct. This sequence of five events covers 4 different valid transitions (both “NotAvailable” events correspond to the same transition between S1 and S3). This test case covers 4 out of 7 valid transitions
b) Is correct. This sequence of five events covers 5 different transitions (the first “Available” event corresponds to a transition between S1 and S2, and the second “Available” event corresponds to a transition between S3 and S2, so two different transitions are covered). This test case covers 5 out of 7 valid transitions and achieves the highest valid transitions coverage
c) Is not correct. This sequence of five events covers 3 different transitions (both “Available” events correspond to the same transition from S1 to S2; both “ChangeRoom” events correspond to the same transition from S2 to S1). This test case covers 3 out of 7 valid transitions
d) Is not correct. This sequence of five events does not represent a feasible test case, because after “Cancel” the system ends up in the End state and no further valid transitions can be executed

Explanation / Rationale

We want to run test cases according to their priorities, but we also need to consider the dependencies.
If we only consider priorities, we want to first run TC 5 and TC 7 (highest priority), then TC 1, TC 3, and TC 4, and finally TC 2 and TC 6 (lowest priority).
However, in order to run TC 7, we need to first run TC 4.
In order to run TC 5, we need to run TC 4 and TC 2, but TC 2 is blocked by TC 1, which should be run prior to TC 2.
So, in order to run priority 1 test cases as early as possible, the first five test cases should be: TC 4 - TC 7 - TC 1 - TC 2 - TC 5.
Next, we need to run TC 3, because it has higher priority than TC 6.
Thus the full schedule will be TC 4 – TC 7 – TC 1 – TC 2 – TC 5 – TC 3 – TC 6.
So, the sixth test case will be TC 3.

Thus:
a) Is correct
b) Is not correct
c) Is not correct
d) Is not correct

Explanation / Rationale

a) Is correct. This is something that can (and should) be checked before the code is submitted to version control
b) Is not correct. This is something that can be checked after step (2) is performed, because merge conflict reporting can be done after the code is submitted and merged
c) Is not correct. This fits better as the entry criterion for step (3)
d) Is not correct. This fits better as the exit criterion for step (3)

Explanation / Rationale

a) Is correct. The client is in a different location and time zone, so it may be difficult to communicate face-to-face
b) Is not correct. Dashboards are usually available to any user at any time, so the difference in time zones will not be as much of a hindrance to communication as verbal, face-to-face communication
c) Is not correct. Although the time difference between Europe and America is several hours, and this may cause some inconvenience, it's certainly not as great as with communicating face-to-face
d) Is not correct. Video conferencing tools are a convenient means of communication. Although communication between Europe and America during working hours usually requires one party to connect in the very early or very late hours, this is not as much of an inconvenience as verbal, face-to-face communication

Explanation / Rationale

a) Is not correct. Assuming that testers could check the ease of changing the currency exchange system then it would be done by maintainability testing rather than maintenance testing, so this is not a trigger for maintenance testing
b) Is correct. A system modification (such as a fix or enhancement) is an example of a trigger for maintenance testing. The removal of the refund option of the currency exchange system was a fix that would lead to maintenance testing
c) Is not correct. If the agile team has started developing a user story that adds a new customer loyalty feature to the currency exchange system, then this will result in them testing the new feature, and then they would perform regression testing. No maintenance testing is required in this situation
d) Is not correct. Reconfiguration of the currency exchange system to support both the local language and English currency transactions is not a system modification, a change to the operational environment, or a system retirement, which are the three triggers for maintenance testing

Explanation / Rationale

a) Is correct. This principle means that if the same tests are repeated over and over again, eventually these tests no longer find any new defects. This is probably why the tests all passed in this release as well
b) Is not correct. This principle says about the mistaken belief that just finding and fixing a large number of defects will ensure the success of a system
c) Is not correct. This principle says that a small number of components usually contain most of the defects
d) Is not correct. This principle states that testing all combinations of inputs and preconditions is not feasible

Explanation / Rationale

a) Is correct. The primary benefit of independence in testing is that testers are more likely to identify different types of failures and defects compared to developers, due to their varied backgrounds, technical viewpoints, and potential biases, including cognitive bias. However, the main disadvantage of independence in testing is that testers may become isolated from the development team, leading to communication problems, a lack of collaboration, and potentially an adversarial relationship, with testers being blamed for delays and bottlenecks in the release process
b) Is not correct. A developer’s familiarity with the code does not mean that they rarely find defects in it, instead this familiarity means they can efficiently find many defects in their own code. And, rather than developers and testers having a shared background, developers having a different background to testers is normally cited as the reason that testers and developers find different kinds of defects
c) Is not correct. Testing can be conducted at different levels of independence, ranging from no independence for the author to very high independence for testers from outside the organization. In most projects, multiple levels of independence are utilized, with developers performing component and component integration testing, the test team performing system and system integration testing, and business representatives performing acceptance testing. So, testers can be in the developer’s team and do not need to come from outside the organization. Knowledge of the application domain will change from case-to-case and is not dependent on the level of independence
d) Is not correct. Testing can be conducted at different levels of independence, ranging from no independence for the author to very high independence for testers from outside the organization, with testers from outside the developer’s team generally more independent than testers from within the team. However, there is more reason to believe that testers from outside the team are likely to be more isolated from the developers and so are more likely to be blamed for delays in product release

Explanation / Rationale

a) Is correct. For a complex configuration item (e.g., a test environment), CM records the items it consists of, their relationships, and versions
b) Is not correct. CM tools do not execute test cases and do not calculate coverage
c) Is not correct. A CM tool is not a license management tool
d) Is not correct. CM tools do not generate test data

Explanation / Rationale

a) Is not correct. Testers should review work products as soon as drafts are available to enable early testing as part of a shift-left approach. If they waited until the next development phase, then unnecessary development (and test) work could be started on unreviewed, flawed work products
b) Is correct. Testers should review work products as soon as drafts are available to enable early testing as part of a shift-left approach
c) Is not correct. Testers typically review work products that form the test basis as part of test analysis, not before test analysis and design
d) Is not correct. Testers should review work products as soon as drafts are available to enable early testing as part of a shift-left approach. Waiting until they are published means that any defects that could be found by tester review will be in the published document

Explanation / Rationale

a) Is not correct. It is often possible to use dynamic testing to cause a test object to fail in ways that could never be achieved by the users, such as by using fault injection. However, if the failure can never occur with real end users, then identifying it is not especially valuable as testing is ultimately aimed at improving the work product for the end users. Spending time testing for failures that cannot occur with real users is not an efficient use of a tester’s time
b) Is not correct. Static testing in the form of static analysis is used by developers to identify defects in their program code earlier than can be achieved through dynamic testing. Note, however, that static testing (and static analysis) is used to detect defects, not failures, which are found by dynamic testing. Thus it is the use of the term ‘failures’ that makes this an incorrect option
c) Is not correct. Static analysis directly detects anomalies in code, which may be defects, and this is normally for the developer, not the customer. The provision of evidence for release by the use of static analysis of elements that provide no output is nonsense
d) Is correct. Reviews are a form of static testing that can be applied from the very start of the software development lifecycle and are used to find defects that can be removed before subsequent development activities waste effort on faulty requirements. If the defects are not detected and removed early on, then when the defect is found derived work products, such as the design and code, will need to be changed as they were based on faulty requirements

Explanation / Rationale

a) Is not correct. Traceability is the relationship between two or more work products, not between different versions of the same work product
b) Is not correct. Maintenance testing is about testing changes; it is not related closely to versioning
c) Is correct. To support testing, configuration management may involve the version control of all test items
d) Is not correct. Requirements engineering is the elicitation, documentation, and management of requirements; it is not closely related to test script versioning

Explanation / Rationale

Considering each of the listed test activities and their output testware:

A. Test analysis - prioritized test conditions (4) (e.g., acceptance criteria), and defect reports for defects identified in the test basis
B. Test design - prioritized test cases, test charters, coverage items (1), test data requirements, and test environment requirements
C. Test implementation - test procedures, automated test scripts, test suites, test data, test execution schedule (3), and test environment elements such as stubs, drivers, simulators, and service virtualizations
D. Test completion - test completion report, documented lessons learned, action items for improvement, and change requests (2) (as product backlog items)

Thus:
a) Is correct. The correct match is: 1B, 2D, 3C, 4A
b) Is not correct
c) Is not correct
d) Is not correct

Explanation / Rationale

Only third-party executable code cannot be reviewed.
Thus:
a) Is not correct
b) Is not correct
c) It is correct
d) Is not correct

Explanation / Rationale

a) Is not correct. We want to check that Special users have the rights of Regular users, so we need to test access rights for a Special user, not for a Regular user
b) Is not correct. We want to check that Special users have the rights of Regular users, so we need to test access rights for a Special user, not for a Regular user
c) Is not correct. There is no floor 5 described in the acceptance criteria. The test cases should not extend the scope of the user story. But even if we would like to perform negative testing, this test is not directly related to AC3
d) Is correct. This way we can check if a Special user can access floors which are accessible to a Regular user

Explanation / Rationale

a) Is correct. The basic concept behind error guessing is that the tester tries to guess what errors may have been made by the developer and what defects may be in the test object based on past experience (and sometimes checklists)
b) Is not correct. Although a testers who used to be a developer may use their personal experience to help them when performing error guessing, the test technique is not based on prior knowledge of development
c) Is not correct. Error guessing is not a usability technique for guessing how users may fail to interact with the test object
d) Is not correct. Duplicating the development task has several flaws that make it impractical, such as the tester having equivalent skills to the developer and the time involved to perform the development. It is not error guessing