What Role Does an Interface Play When Using a Mock

Multiple Choice

What role does an interface play when using a mock class?

A) The mock class should be an interface that will be implemented by the real class.
B) The real class should be an interface that will be implemented by the mock class.
C) Interfaces are not involved when using mock classes.
D) An interface should be implemented by both the real class and the mock class to guarantee that the mock class accurately simulates the real class when used in a program.