ISTQB CT-UT Exam With Confidence Using Practice Dumps

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.

SUS (System Usability Scale), SUMI (Software Usability Measurement Inventory), and WAMMI (Website Analysis and Measurement Inventory) are all validated, standardized usability questionnaires that support benchmarking. They allow comparison against known usability scores from a wide variety of systems. These instruments provide numeric scores that can be interpreted using benchmark datasets or industry standards. Therefore, all three—i, ii, and iii—are true, making D the correct answer.

The described issue violates the usability heuristic “User control and freedom,” as defined by Jakob Nielsen. This principle emphasizes that users should have the ability to undo and redo actions and navigate freely without being trapped in irreversible sequences. In the scenario, users are forced into the checkout process without a clear way to return or correct mistakes, except through the unreliable and disruptive back button. This design flaw undermines user autonomy and can result in lost progress or frustration.