Nick Is Extremely Anxious Whenever He Takes a Test

Nick is extremely anxious whenever he takes a test. From a classical conditioning perspective, a teacher can best reduce his anxiety by:

A) Giving him a few extremely difficult tests at first, and then gradually giving him easier ones
B) Giving him a few easy tests while he is feeling relaxed
C) Reinforcing him for each test question he answers correctly
D) Reassuring him that he can do well if he tries hard