Mariah developed a fear of the water when she fell off a river raft last summer. This year, she took swimming lessons and thought she had finally overcome her fear of water. She was eagerly looking forward to an upcoming rafting trip, but as soon as she stepped onto the raft, she was instantly terrified again. This illustrates the classical conditioning process known as:.
a. second-order conditioning.
b. stimulus generalization.
c. extinction.
d. spontaneous recovery.