Which of the following set of test types would be most appropriate to verify the non-functional requirements expressed in this statement?

A client-server system for a web development must support a minimum of 200 enquiries per hour. In peak times, it must be available 24 hours x 7 days due to the critical nature of the application, and must have a response time lower than 20 seconds during peak loads.

Which of the following set of test types would be most appropriate to verify the non-functional requirements expressed in this statement?
A . Performance, Usability, Regression.
B . System, Load, Fail-over.
C . Performance, Load, Stress.
D . Load, Volume and Component.

Answer: C