CAPM Practice: Validate requirements through product delivery

Usability testing reveals requirements gaps that functional testing misses: a feature may work exactly as specified but users struggle to find it, understand it, or complete their tasks with it. These usability failures represent missing requirements around user experience.

**Why not B:** Usability testing validates far more than visual design. It assesses whether users can accomplish their goals effectively, including navigation, task flows, error recovery, and overall ease of use. Limiting it to visual design misses the behavioral and experiential aspects it uncovers.

**Why not C:** Usability testing does not validate non-functional performance requirements like response time or throughput. It validates the user experience — whether users can effectively accomplish tasks — which is a distinct concern from system performance metrics.

**Why not D:** Usability testing and user acceptance testing serve different purposes. UAT confirms the solution meets acceptance criteria and business needs. Usability testing specifically evaluates how easily and effectively users can accomplish their goals, revealing UX gaps that functional testing misses.