Explanation / Rationale

There are five columns in the decision table. Each test case covers one of them.

TC1 and TC2 both cover Rule 4
TC3 and TC4 both cover Rule 2
TC5 covers Rule 5

So, these five test cases cover three out of five columns, achieving a coverage of (3/5)*100% = 60%. Therefore, option b) is the CORRECT option.
Thus:
a) Is not correct
b) Is correct
c) Is not correct
d) Is not correct

Explanation / Rationale

a) Is correct. Value “1” covers “length incorrect” and covers “number of different digits incorrect”, however the system would not validate against this partition when hitting the first incorrect partition. Value “1111” covers “length correct” and “number of different digits incorrect. Value “1234” again covers “length correct” and also “number of different digits correct”
b) Is not correct. These three values achieve full coverage of the equivalence partitions, but full coverage can be achieved with two values
c) Is not correct. These two values only cover “number of different digits
d) Is not correct. These two values does not cover “number of different digits incorrect” equivalence partition

Explanation / Rationale

Considering:

• The test basis for acceptance testing is the user’s business needs (1D)
• Communication between components is tested during component integration testing (2B)
• Failures in logic can be found during component testing (3A)
• Business rules are the test basis for system testing (4C)

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

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 not correct. Strong communication skills, active listening, and teamwork abilities enable a tester to interact effectively with all stakeholders, however a deep knowledge of a variety of computer games that allowed them to get on well with one developer is not an example of a generic skill useful to testers
b) Is correct. Domain knowledge that can be used to understand and communicate with end-users and business representatives is one of the generic skills required by testers. A tester with experience as a pilot would make them better able to appreciate the acceptance criteria for the helicopter control system
c) Is not correct. Although programming skills could be considered as technical knowledge which can increase efficiency when utilizing some test tools, it is unlikely that these skills would improve their communication with business analysts
d) Is not correct. Although thoroughness, attention to detail, curiosity, and a methodical approach to identifying hard-to-find defects are all useful generic skills for testers, it is doubtful they would be generating test cases prior to starting exploratory testing. This is because one of the main tenets of exploratory testing is that the test cases are generated during the testing, not scripted in advance

Explanation / Rationale

Considering each of the listed review types:

1. Technical review - This type of review is performed by technically qualified reviewers and led by a moderator. The objectives are to gain consensus and make decisions on technical problems while also evaluating quality and building confidence in the work product, generating new ideas, motivating and enabling authors to improve, and detecting anomalies
2. Informal review - The main objective is to detect anomalies. The process is not defined and does not require formal documented output
3. Inspection - This is the most formal review type, and it follows the complete generic review process. The primary objective is to find the most anomalies, and other objectives include evaluating quality and building confidence in the work product, motivating and enabling authors to improve, and collecting metrics that can be used to enhance the software development life cycle (SDLC), including the inspection process. The author cannot act as the review leader or scribe
4. Walkthrough - Led by the author, this type of review serves various objectives such as evaluating quality and building confidence in the work product, educating reviewers, gaining consensus, generating new ideas, motivating and enabling authors to improve, and detecting anomalies. Reviewers might perform an individual review before the walkthrough, but this is not mandatory

A. Includes objectives such as gaining consensus, generating new ideas, and motivating authors to improve (A)
B. The main objective is detecting potential defects and it generates no formal documented output (D)
C. The main objective is detecting potential defects and it requires metrics collection to support process improvement (C)
D. Includes objectives such as educating reviewers, gaining consensus, generating new ideas and detecting potential defects (B)

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

Explanation / Rationale

a) Is not correct. Validating that documented requirements are met is incorrect as validation is concerned with meeting user requirements and expectations, while verification is concerned with meeting specified requirements, so this would be correct if we replaced ‘validating’ with ‘verifying’
b) Is correct. Causing failures and identifying defects is probably the most common objective of dynamic testing
c) Is not correct. Initiating errors and identifying root causes is incorrect because testers do not initiate errors, they try to cause failures. Errors are typically made by developers (and cannot really be initiated) and result in defects, which testers attempt to identify either directly through static testing or indirectly through failures with dynamic testing. Identifying root causes is useful but is part of debugging, which is a separate activity to testing
d) Is not correct. Verifying the test object meets user expectations is incorrect as verification is concerned with checking specified (documented) requirements are met, while validation is concerned with meeting user requirements and expectations, so this would be correct if we replaced ‘verifying’ with ‘validating’

Explanation / Rationale

a) Is not correct. Test automation does not introduce unknown regressions in production
b) Is correct. Wrong allocation of effort to maintain testware is a risk
c) Is not correct. Test tools must be selected so that they and their testware can be relied upon
d) Is not correct. The primary goal of test automation is to reduce manual testing. So, this is a benefit, not a risk

Explanation / Rationale

a) Is not correct. Dynamic testing does cause failures (from which defects can then be located and fixed). However, debugging is concerned with locating defects and fixing these defects. Therefore, debugging does not fix failures
b) Is not correct. Both testing and debugging contribute to improving the quality of the test object, so should really both be considered positively. Debugging is generally considered to be a positive activity as it is fixing something. Dynamic testing does involve intentionally causing the test object to fail, which is why some people consider it a negative activity, but that is a very narrow view (and not one typically held by testers). Both positive and negative test cases are possible. Positive test cases check that the test object correctly performs what it is supposed to do, while negative testing checks that the test object does not do what it is not supposed to do
c) Is correct. Testing determines that defects exist either directly through observation of the defect in reviews (or by a tool in static analysis), or indirectly by causing a failure in dynamic testing. Debugging is a separate activity from testing (normally performed by developers) and is concerned with locating defects (only for dynamic testing) and fixing the defects
d) Is not correct. The causes of defects are typically human errors. Testing finds defects either directly through static testing, or indirectly by causing failures in dynamic testing, and debugging fixes defects. So, testing does not find the cause of defects and debugging does not fix the causes of defects

Explanation / Rationale

Consider:

i. These behaviors are easily detectable while the software is running. Hence, dynamic testing shall be used to identify them
ii. This is an example of deviations from standards, which is a typical defect that is easier found with static testing
iii. If the software is executed during the test, it is dynamic testing
iv. Identifying defects as early as possible is the test objective of both static testing and dynamic testing
v. This is an example of gaps in the test basis traceability or coverage, which is a typical defect that is easier found with static testing

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

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

The following three transitions:

“REQUESTING -> CONFIRMED”
“WAITING LIST -> CONFIRMED”
“WAITING LIST -> END”

cannot appear in the same test case, which suggests that at least three test cases are required. All the other transitions can appear in combination with one or more of these three transitions, so we need a minimum of three test cases. In fact, only three sequences are possible:

TC1: START (Room request) → REQUESTING (Available) → CONFIRMED (Pay) → END
TC2: START (Room request) → REQUESTING (Not available) → WAITING LIST (Available) → CONFIRMED (Pay) → END
TC3: START (Room request) → REQUESTING (Not available) → WAITING LIST (Cancel) → END

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

Explanation / Rationale

a) Is correct. When a system is retired, this can require testing of data migration, which is a form of maintenance testing
b) Is not correct. Regression testing verifies whether a fix accidentally affected the behavior of other parts of the code, but now we are talking about data migration to a new system
c) Is not correct. Component testing focuses on individual hardware or software components, not on data migration
d) Is not correct. Integration testing focuses on interactions between components and/or systems, not on data migration

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

Considering each of the listed tool categories and their descriptions:

A. Static testing tools – support the tester in performing reviews and static analysis (4)
B. Tools supporting scalability and deployment standardization – For example, virtual machines, containerization tools (3)
C. DevOps tools – support the DevOps delivery pipeline, workflow tracking, automated build process(es), continuous integration/continuous delivery (CI/CD) (1)
D. Collaboration tools – facilitate communication (2)

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

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. While the sentence is true, it does not provide much value for the developer
b) Is correct. From the test results it seems that the system ignores duplicates and sorts the list disregarding the repetitions. This is probably the cause of failures in TC3, TC4, TC5. Such information may help the developer to find the defect and fix it more efficiently
c) Is not correct. The system does not fail in sorting negative numbers. The problem is rather in disregarding duplicates
d) Is not correct. The test cases TC3, TC4 and TC5 fail, but we aren’t aware that the test cases have any defects

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

a) Is not correct. This is a common characteristic of white-box test techniques. Test conditions, test cases, and test data are derived from a test basis that may include code, software architecture, detailed design, or any other source of information regarding the structure of the software.
b) Is not correct. This is a common characteristic of white-box test techniques. Coverage is measured based on the items tested within a selected structure and the technique applied to the test basis
c) Is correct. This is a common characteristic of experience-based test techniques. This knowledge and experience include expected use of the software, its environment, likely defects, and the distribution of those defects is used to define tests
d) Is not correct. This is a common characteristic of black-box test techniques. Test cases may be used to detect gaps within requirements and the implementation of the requirements, as well as deviations from the requirements

Explanation / Rationale

a) Is not correct
b) Is not correct
c) Is not correct
d) Is correct. This rule holds for all SDLC models

Explanation / Rationale

Given the following description of 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. The systematic identification of test conditions as coverage items often involves using test techniques both during test analysis and as part of the test design activity.
From the above description, it can be seen that test techniques are often used in the test analysis and test design activities. Boundary value analysis and equivalence partitioning are test techniques.
a) Is not correct. Test implementation is not likely to involve the use of test techniques as it is mostly concerned with assembling test cases into test procedures, while test techniques create test cases
b) Is correct. Test design is likely to involve the use of test techniques to create test cases from test conditions and coverage items
c) Is not correct. Test execution is not likely to involve the use of test techniques as it is mostly concerned with executing test procedures (and so test cases), while test techniques create test cases
d) Is not correct. Test monitoring is not likely to involve the use of test techniques. Test monitoring is mostly concerned with ongoing checks to ensure the plan is being followed, while test techniques create test cases
e) Is correct. Test analysis is likely to involve the use of test techniques to identify test conditions

Explanation / Rationale

a) Is not correct. The approval of the budget is an example of an entry criterion. It would make no sense to approve the budget for some activity that has already been done
b) Is correct. Running out of budget can be viewed as a valid exit criterion
c) Is not correct. Availability of resources is an example of an entry criterion for testing
d) Correct. Coverage is a measure of thoroughness, so it is a typical exit criterion
e) Is not correct. This is an example of an entry criterion, checked before the project starts

Explanation / Rationale

“Small garden” and “large garden” can go only with “ground floor”, so we need two test cases with “ground floor” which cover these two “garden type” partitions.
We need two more test cases to cover the two other “floor” partitions and a remaining ”garden type” partition of “no garden”.
We need a total of four test cases:

TC1 (ground floor, small garden)
TC2 (ground floor, large garden)
TC3 (first floor, no garden)
TC4 (second or higher floor, no garden)

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

Explanation / Rationale

a) Is not correct. The test pyramid emphasizes having a larger number of tests at the lower test levels
b) Is correct. It is not true that near the top of pyramid, test automation should be more formal
c) Is not correct. Usually component testing and component integration testing are automated using API-based tools
d) Is not correct. For system testing and acceptance testing, the automated tests are typically created using GUI-based tools

Explanation / Rationale

a) Is not correct. Acceptance criteria are the conditions used to decide whether the user story is ready. They cannot show work progress
b) Is not correct. Defect reports inform about the defects. They do not show work progress
c) Is not correct. Test completion report can be created after the iteration is finished, so it will not show the progress continuously within an iteration
d) Is correct. Burndown charts are a graphical representation of work left to do versus time remaining. They are updated daily, so they can continuously show the work progress

Explanation / Rationale

Because TC1 and TC3 failed in Execution 1 (i.e., test (1) and test (3)), test (4) and test (6) are confirmation tests.
Because TC2 and TC3 failed in Execution 2 (i.e., tests (5) and (6)), test (8) and test (9) are also confirmation tests.
TC2 passed in Execution 1 (i.e., test (2)), so test (5) is a regression test.
TC1 passed in the Execution 2 (i.e., test (4)), so test (7) is also a regression test.
Thus:
a) Is not correct
b) Is correct
c) Is not correct
d) Is not correct

Explanation / Rationale

a) Is not correct. Test progress reports are mostly used during test monitoring and control, and test completion, not during test design
b) Is correct. A test completion report is prepared during test completion, when a project, test level, or test type is complete and when, ideally, its exit criteria have been met. This report uses information from test progress reports and other data
c) Is not correct. Test progress reports are mostly used during test monitoring and control, and test completion, not during test analysis
d) Is not correct. Test progress reports are most used during test monitoring and control, and test completion, not during test planning

Explanation / Rationale

Considering each of the listed risks and their mitigations:

1. Long system responses (1) can be tested in performance testing (B)
2. Changes of consumers’ preferences (2) are usually out of our control, so usually we accept this risk (A)
3. Flooding of the server room (3) can cause significant loss, so we should transfer the risk, e.g., by buying an insurance policy (D)
4. That patients above a certain age receive inaccurate reports (4) suggests a potential boundary problem, which can be effectively detected with techniques like BVA (C)

Thus:
a) Is not correct
b) Is not correct
c) Is correct. The correct combinations of risk and mitigation are: 1B, 2A, 3D and 4C
d) Is not correct

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 not correct. The root cause is the distraction that the programmer experienced while programming
b) Is not correct. Accepting invalid inputs is a failure
c) Is not correct. The error is the mistaken thinking that resulted in putting the defect in the code
d) Is correct. The problem in the code is a defect

Explanation / Rationale

Considering:

• Usability testing is in Q3 (1 – C)
• Component testing is in Q1 (2 – A)
• Functional testing is in Q2 (3 – B)
• Reliability testing is in Q4 (4 – D)

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

Explanation / Rationale

Using the three-point estimation technique, the final estimate (E) is calculated as:

E = (a + 4*m + b) / 6,

where a is the most optimistic estimate, m is the most likely estimate, and b is the most pessimistic estimate.

Thus:
a) Is correct. In this case, the estimate for executing a single test case is:

E = (1h + 4*3h + 8h) / 6 = 3.5 hours

So, the total time needed for the tester to execute 4 test cases is:

3.5h * 4 = 14 hours

b) Is not correct
c) Is not correct
d) Is not correct

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. Checklists should contain test conditions to be verified. This is an example of an error, not a test condition; even if the tester was able to deduce some potential test conditions from the examples of errors, this error description is too general
b) Is not correct. Checklists should not contain items that are better suited as exit criteria. This is an example of an exit criterion
c) Is not correct. Checklists should not contain items that are too general. This is a very general item, which practically describes the goal of testing
d) Is correct. This is an example of a test condition that can be checked by a human

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 correct. The ‘tests wear out’ principle is concerned with the idea that repeating identical tests on unaltered code is unlikely to uncover novel defects and therefore, modifying tests may be essential. By using high-level test conditions to generate new tests each time, the tests will not be identical and should not ‘wear out’
b) Is not correct. The ‘absence-of-defects fallacy’ principle is concerned with ensuring that users’ needs are fulfilled even if lots of testing is done and no defects are found (i.e., validation is also necessary). The use of high-level test conditions to generate test cases and execute tests does not directly address this concern
c) Is not correct. The ‘early testing saves time and money’ principle is concerned with fixing defects early on to prevent the occurrence of subsequent defects in derived work products, thereby reducing costs and the likelihood of failures. This is typically addressed by starting testing (both static and dynamic) as early as possible, but this is not addressed by using high-level test conditions to generate test cases and execute tests
d) Is not correct. The ‘Defects cluster together’ principle is concerned with the distribution of defects in a system, which typically follows a Pareto distribution. The use of high-level test conditions to generate test cases and execute tests does not address this concern, which is typically addressed by risk-based testing

Explanation / Rationale

a) Is correct. Test-Driven Development (TDD) is a well-known example of a test-first approach to development
b) Is not correct. Coverage-Driven Development is not a correct example of a test-first approach to development
c) Is not correct. Quality-Driven Development is not a correct example of a test-first approach to development
d) Is not correct. Feature-Driven Development is not an example of a test-first approach to development, but is, instead, an agile software development methodology based around delivering features (as opposed to user stories in Scrum)

Explanation / Rationale

a) Is not correct. In most cases both black-box test techniques and experience-based test techniques can be used for the same test objects
b) Is not correct. Both black-box test techniques and experience-based test techniques can be used at all test levels
c) Is correct. Black-box test techniques (also known as specification-based techniques) are based on an analysis of the specified behavior of the test object without reference to its internal structure. So, the test basis is usually a specification. Experience-based test techniques effectively use the knowledge and experience of testers for the design and implementation of test cases. This means that the tester, when designing tests, may not use the specification at all
d) Is not correct. Experience-based test techniques can detect defects that may be missed using black-box (and white-box) test techniques. Hence, experience-based test techniques are complementary to black-box test techniques and white-box test techniques and both black-box test techniques and experience-based test techniques can be used in all SDLCs

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. Confirmation testing to check that the updates have resulted in a correct implementation is necessary, however, it would then be sensible to perform regression testing to ensure that no defects have been introduced or uncovered in unchanged areas of the system
b) Is correct. Confirmation testing will check that the updates have resulted in a correct implementation, and then regression testing will be used to ensure that no defects have been introduced or uncovered in unchanged areas of the system
c) Is not correct. Regression testing should be used to ensure that no defects have been introduced or uncovered in unchanged areas of the system when the update was made, however it is also necessary to perform confirmation testing that will check that the updates have resulted in a correct implementation
d) Is not correct. Confirmation testing will check that the updates have resulted in a correct implementation, and regression testing will be used to ensure that no defects have been introduced or uncovered in unchanged areas of the system. However, when performed (i.e., when an update needs to be tested), confirmation testing precedes regression testing