In a residential treatment facility for troubled youth, adolescent children receive large, colored buttons when they hang up their clothes, make their beds, and come to meals on time. The children return the buttons to staff members to receive bedtime snacks or TV time.
This BEST illustrates an application of:

A. operant conditioning.
B. humanistic therapy.
C. systematic desensitization.
D. stress inoculation training.
E. virtual reality exposure therapy.
F. None of the listed answers are correct