Joshua, an 8-Year-Old Boy, Has Been Diagnosed with Conduct Disorder

Joshua, an 8-year-old boy, has been diagnosed with conduct disorder. He has been undergoing therapy for the past few months. Joshua's psychologist has advised his parents to reward him whenever he is obedient and does what has been asked of him. This technique is most likely to be part of

A) drug therapy.
B) play therapy.
C) art therapy.
D) behavior therapy.