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.
References:
Brooke, J. (1996). SUS: A Quick and Dirty Usability Scale.
Usability.gov: System Usability Scale (SUS)
ISO/IEC 25062 - Common Industry Format for Usability Test Reports
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