Sully has a painful experience at the dentist's office. The next time his mother brings him to the dentist's office, Sully gets tense and anxious. Sully then does not go to see the dentist for several years. On his next visit, Sully employs a method based on classical conditioning that reduces anxiety by getting himself to associate relaxation with going to the dentist. This is an example of which of the following? A. Discriminative learning
B. Systematic desensitization
C. Higher-order conditioning
D. Stimulus generalization
E. Extinction