Which of the following is a type of functional testing? a. Unit testing b . Performance testing c. Load testing d. Security testing e. Usability testing

The correct answer is **b. Performance testing**.While unit, load, security, and usability testing are all important types of software testing, they are *not* considered functional testing. Functional testing verifies that a software application functions as specified in the requirements document. Performance testing, on the other hand, focuses on how the system performs under various conditions (e.g., response time, stability under load). It assesses the system's responsiveness, stability, scalability, and resource usage. Therefore, it's a type of non-functional testing. The other options are also types of non-functional testing or specific testing types that fall outside the scope of functional testing.