After the Successful Extinction of Your Son's Whining for a Toy

Multiple Choice

After the successful extinction of your son's whining for a toy while you are shopping, you go shopping several weeks later and he begins to whine for a toy as if he is "just checking to see if the rules have changed back." This situation illustrates

A) token reinforcement.
B) spontaneous recovery.
C) stimulus generalization.
D) stimulus discrimination.