To prevent usability testing from exceeding budget, active monitoring and control of project resources are critical. The best practice is to regularly check consumed time, costs, and effort against the original estimates, allowing timely adjustments to scope or resources. This is a classic quality control practice aligned with ISO 9001 principles and standard project management methodologies. Option A relates to test preparation, option C concerns reporting and communication, and option D applies after test execution. Only option B deals directly with budget control during the test.

When a customer emphasizes the importance of accessibility, it means they are concerned with ensuring that users with disabilities or limitations are not excluded from using their products or services. Accessibility is about inclusiveness—providing equal access and opportunity to all users regardless of physical or cognitive ability. Option C directly reflects this understanding. The other options (A, B, and D) are aspects of usability or development methodologies but do not relate to addressing the needs of users with disabilities, which is the core focus of accessibility.

Positive usability findings play a key role in reinforcing what is working well in the user interface. They help:

A: Build developer confidence and soften criticism when pointing out issues.

C: Provide a complete picture of usability strengths and weaknesses.

D: Inform developers what should remain unchanged during redesign.

However, B is incorrect because justifying usability test costs should not rely solely on positive findings. Cost justification should come from the overall impact of usability on user satisfaction, performance, and business outcomes—not just good results.

The System Usability Scale (SUS) is a standardized, reliable tool used to measure perceived usability. It consists of 10 items with five response options (from strongly agree to strongly disagree). It is widely used due to its simplicity and effectiveness in providing a single score to reflect a user’s overall satisfaction with a system. Option A refers to ISO's definition of usability testing, B describes a task in usability testing, and D refers to a usability requirement, not SUS. Therefore, the correct description of SUS is option C.

Usability labs provide a controlled environment that offers several advantages for observing and recording usability test sessions. Specifically, they allow for easy observation of participants (ii), standardized conditions for each session (iv), and facilitate audio and video recording for detailed analysis (v). However, the context is not natural (i), because the lab is an artificial setting rather than the user’s actual environment. Also, setting up a professional usability lab is not inexpensive (iii); it typically involves significant costs for equipment, space, and staffing. Therefore, options ii, iv, and v are true, while i and iii are false.

A usability test script is a structured document used by the moderator to ensure consistency across test sessions. It typically includes pre-session briefing text, pre- and post-session interview questions, and the specific usability tasks to be performed. However, it does not include answers to the test questions, as usability tests focus on observing user behavior and performance—not testing users’ knowledge. Providing answers would bias results and invalidate findings. Thus, option D is incorrect and the best choice.

Common mistakes in usability testing include:

Ignoring critical results (ii): A significant issue if findings are not acted upon.

Scheduling the test too late (iv): This can lead to usability problems being discovered too late to be addressed effectively.

Having the wrong focus (v): For instance, focusing on aesthetics instead of usability goals.

Option i ("user is too active") is not a problem—active participation is necessary. Option iii ("no observers involved") is not a typical mistake, since tests can still be valid even with recorded sessions and later review. Hence, the correct answer is A: ii, iv & v are true.