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. 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. 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

a) Is not correct. The document does not refer to the test object’s internal structure but specifies the desired behavior of the test object. Therefore, white-box test techniques will not be helpful in designing test cases
b) Is correct. The document is a requirement that specifies the desired behavior of the test object. Therefore, the most suitable test techniques in this case are the black-box test techniques (e.g., Boundary Value Analysis or Decision Table Testing)
c) Is not correct. Although experience-based test techniques can be used to design test cases based on this document, black-box test techniques will be more suitable. The document describes a precise business rule and, in addition, wording like "exceeds $100" suggests the existence of important equivalence partition boundaries that should be tested using black-box test techniques like boundary value analysis
d) Is not correct. Risk-based test techniques are not a recognized type of test technique

Explanation / Rationale

a) Is correct. System testing examines the behavior and capabilities of the complete system and covers non-functional testing of quality characteristics, which includes security testing. This type of testing is often performed by an independent test team based on system specifications
b) Is not correct. System integration testing examines the interfaces with other systems and external services
c) Is not correct. Beta testing is a type of acceptance testing performed at an external site by roles outside the development organization
d) Is not correct. Component integration testing involves testing the (interfaces and) interactions between components of a system, such as the user interface and database

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

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 correct. The test plan may include test data requirements (as part of the test approach), but not the detailed test data for test cases. Test data is part of the test cases, not the test plan. Also, it is usually impossible to define such data when the test plan is created, because it is not exactly known what the components will look like
b) Is not correct. One of the purposes of a test plan is to help ensure that the performed test activities will meet the established criteria, by including entry criteria and exit criteria. The code coverage criteria are an example of such criteria for the component test level
c) Is not correct. Documentation templates are typical content of a test plan. This helps to facilitate communication between the stakeholders by defining a standard way of communicating or reporting
d) Is not correct. One of the purposes of a test plan is to demonstrate that testing will adhere to the existing test policy and test strategy, or to explain why the testing will deviate from them. This is an example of explaining the deviation, regarding the test levels that will be (or will not be) followed

Explanation / Rationale

a) Is not correct. The combination (T, T, F) does not match any rule. This is an example of omission, not a contradiction
b) Is not correct. The combination (T, F, T) matches only one column, R2, so there is no contradiction
c) Is not correct. Both combinations (T, T, T) and (F, T, T) match only one column, R1, so there is no contradiction
d) Is correct. The combination (F, F, F) matches both R2 and R3, but R2 and R3 have different actions, so this shows a contradiction between R2 and R3.

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

Considering each of the listed testware, and the test activity that produces it:

i. The test completion report is an output of the test completion activity
ii. Data held in a database used for test inputs and expected results is the test data - output of test implementation activity
iii. The list of elements needed to build the test environment is the test environment requirements - output of test design activity.
iv. Documented sequences of test cases in execution order are the test procedures - output of test implementation activity
v. Test cases - output of test design activity

Test implementation produces the following outputs: test procedures (iv), automated test scripts, test suites, test data (ii), test execution schedule, and test environment elements such as stubs, drivers, simulators, and service virtualizations.

Thus:
a) Is correct. Items ii and iv in the list are produced as a result of test implementation
b) Is not correct
c) Is not correct
d) Is not correct

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 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. Planning poker can estimate effort for a user story that is already written. It does not help in understanding what should be delivered
b) Is not correct. Reviews are not a collaborative user story writing practice
c) Is not correct. Iteration planning is a project-related practice, used to plan the work, not to understand what needs to be delivered
d) Is correct. Conversation explains how the software will be used and often allows the team to define meaningful acceptance criteria, thus obtaining a shared vision of what should be delivered

Explanation / Rationale

TC1 achieves the highest coverage (4/7 – Req1, Req3, Req4 and Req7), so should be executed first.
Req2, Req5 and Req6 are still not covered.
The next test case that achieves the highest additional coverage of the remaining requirements is TC3, covering 2 out of these 3 requirements (Req5 and Req6). So, TC3 should be executed as the second one.
Now the only requirement still not covered is Req2, which is covered by TC4. Therefore, TC4 should be executed as the third test case.
So, the last test case executed will be TC2.

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

Explanation / Rationale

Consider:

i. Is true. Faster product release and faster time to market is an advantage of DevOps
ii. Is false. Typically, we need less effort for manual tests because of the use of test automation
iii. Is true. Constant availability of executable software is an advantage
iv. Is false. More regression tests are needed
v. Is false. Not everything is automated and setting up a test automation framework is expensive

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

Explanation / Rationale

The ‘exhaustive testing is impossible’ principle is concerned with the fact that it is not feasible to test every possible variation of test inputs in all different circumstances, except in trivial cases. Instead, testing utilizes test techniques, test case prioritization, and risk-based testing to sample from the set of possibilities and focus testing efforts.
a) Is not correct. The principle states that it is not feasible to test everything except in trivial cases. Testing everything would require testing every possible variation of test inputs in all different circumstances, which is generally infeasible as there will be a practically infinite number. Testing every possible specified output will not address this problem as the relationship between inputs and specified outputs can be different for each test object. Sometimes there may be a practically infinite number of possible specified outputs (e.g., when there are several variables representing real numbers), whereas at other times there may be just two specified outputs, such as with a single variable that can be either true or false
b) Is not correct. The principle states that it is not feasible to test every possible variation of test inputs in all different circumstances. This is because for non-trivial systems there is a practically infinite number. Therefore, in practice, documenting all possible test input variations would be impractical as it would take an infinite length of time
c) Is not correct. Starting testing as early as possible with reviews and other static testing approaches will not address the problem of there being too many possible test cases. 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
d) Is correct. The use of equivalence partitioning and boundary value analysis to generate test cases is one way to address the principle as these test techniques provide a systematic way to derive a finite subset of all possible test cases

Explanation / Rationale

a) Is correct. The whole team approach promotes robust communication and collaboration between the team members
b) Is not correct. While the whole team approach prioritizes collective accountability for quality, each individual team member is still equally accountable for quality
c) Is not correct. The whole team approach is about how the team works together, with the aim of higher quality deliverables, but it does not necessarily result in faster deployment to end users
d) Is not correct. When using the whole team approach, testers work with business representatives to create acceptance tests. There is no suggestion that the approach will reduce collaboration with external business users

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. Adequate time for individuals is a success factor
b) Is not correct. Splitting work products into small adequate parts is a success factor
c) Is not correct. Avoiding behaviors that might indicate boredom, exasperation, etc. is a success factor
d) Is correct. During reviews one can find defects, not failures

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

Considering each of the listed task descriptions:

1. The quality characteristics to be evaluated and the exit criteria are selected - (Planning (C): Defining the review scope, purpose, work product to be reviewed, quality characteristics to be evaluated, areas of focus, exit criteria, supporting information such as standards, effort, and timeframes.)
2. Everyone has access to the work product - (Review initiation (B): Ensuring all participants have access to the work product and necessary resources, and clarifying their roles and responsibilities.)
3. Anomalies are identified in the work product - (Individual review (A): Evaluating the work product's quality, identifying and logging anomalies, recommendations, and questions using review techniques like checklist-based and scenario-based reviewing.)
4. Anomalies are analyzed and discussed - (Communication and analysis (D): Analyzing and discussing each anomaly, determining its status, ownership, and required actions, and making review decisions, normally in a meeting. This could include determining the need for a follow-up review.)

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

Explanation / Rationale

a) Is not correct. To ensure successful reviews, it's important to secure management's support for the review process, however that does not mean that they should participate as reviewers
b) Is correct. To ensure successful reviews, it's important to break the work product into parts that are small enough to be reviewed in a reasonable timescale to prevent reviewers from losing focus during individual review or review meetings
c) Is not correct. To ensure successful reviews, it's important to clearly define objectives and measurable exit criteria, without evaluating participants
d) Is not correct. To ensure successful reviews, it's important to break down the review into smaller chunks to prevent reviewers from losing focus during individual review or review meetings. So you should not plan to cover one document per review

Explanation / Rationale

a) Is not correct. The test case is related to viewing previous orders in the order history
b) Is not correct. The test case is related to viewing previous orders
c) Is not correct. The test case is related to viewing previous orders in the order history
d) Is correct. The test case is related to the registration process, which is not discussed in the user story. The user story is about viewing previous orders

Explanation / Rationale

a) Is not correct. The miscalculation of bonuses is a failure by the system, not a defect
b) Is not correct. The system not suitably supporting disabled users is a failure which eventually results in a fine, but the fine itself is not a failure (it appears to be the correct functioning of the regulatory system)
c) Is correct. The error is made by the programmer and this mistake is caused by them working under severe time pressure, which is the root cause of the subsequent defect
d) Is not correct. The poor design of the user interface, which does not suitably address disabled users, is a design defect caused by the designer error. Thus the design of the user interface includes a design defect not a designer error

Explanation / Rationale

The ‘absence-of-defects fallacy’ is concerned with the idea that ensuring correctness in accordance with the requirements (i.e., verifying the absence of implementation defects) does not guarantee user satisfaction with the system. To address this it is also necessary to validate that the system meets users' needs and expectations, fulfills business objectives, and outperforms competing systems.
a) Is not correct. The ‘testing shows the presence, not the absence of defects’ principle explains that while testing can detect the existence of defects in the test object, it is not possible to demonstrate that there are no defects and, therefore, guarantee its correctness. Therefore, explaining that it is not possible for testing to show the absence of defects would partially address this principle, not the ‘absence-of-defects’ fallacy
b) Is correct. By supporting the end user to perform acceptance testing it should be possible to validate that the system meets users' needs and expectations
c) Is not correct. It is not possible to ensure that no implementation defects remain in the delivered system as the ‘testing shows the presence, not the absence of defects’ principle explains that while testing can detect the existence of defects in the test object, it is not possible to demonstrate that there are no defects and, therefore, guarantee its correctness
d) Is not correct. Modifying tests that cause no failures to ensure few defects remain is one way to address the ‘tests wear out’ principle. This 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. This will not validate that the system meets users' needs and expectations

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. A fundamental strength that all white-box test techniques share is that the entire software implementation is taken into account during testing, which facilitates defect detection even when the software specification is vague, outdated or incomplete. This means white-box testing can find defects such as an extra feature added to the code (either accidentally or deliberately) that is not supposed to be there, which black-box testing cannot detect
b) Is not correct. The fact that the coverage can be precisely defined is not the right reason. The achieved level of coverage would have much more impact than the possibility to measure the coverage
c) Is not correct. If the software does not implement one or more requirements, white-box testing is unlikely to detect the resulting defects of omission
d) Is not correct. While this is true, this is not the right answer, because there is no connection between the capability to be used in both static testing and dynamic testing and the claim that white-box testing facilitates defect detection with poor specifications

Explanation / Rationale

There are three equivalence partitions: {…, –2, –1}, {0, 1, 2}, {3, 4, …}.
For 2-value BVA all the boundary values for all the equivalence partitions must be covered.
The boundary values are –1 (for the “temperature too low” partition), 0, 2 (for the “temperature OK” partition) and 3 (for the “temperature too high” partition).

Thus:
a) Is not correct
b) Is not correct
c) Is correct. The correct option is: –1, 0, 2, 3
d) Is not correct

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

Error guessing is about anticipating the errors, defects and failures based on the tester’s knowledge.
a) Is not correct. This is an example of anticipating the developer’s error
b) Is not correct. This is an example of anticipating the defect
c) Is correct. This is an example of a potential root cause of a defect, which is neither an error, defect nor failure, and difficult for the tester to anticipate
d) Is not correct. This is an example of anticipating a failure, perhaps based on experience of previous systems in this application domain

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

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

In branch testing the coverage items are branches, which are represented by the edges of a control flow graph. There are 8 edges in the control flow graph.
Thus:
a) Is not correct
b) Is not correct
c) Is correct
d) Is not correct

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 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

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. 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

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