While Out Trick-Or-Treating for Halloween,at First Billy's Neighbors Had to Remind

Multiple Choice

While out trick-or-treating for Halloween,at first Billy's neighbors had to remind him to say "trick or treat" before they dropped their treats into his bag.As he continued to visit houses in the neighborhood,soon Billy would say "trick or treat" as soon as the neighbors answered the door.The treats he received were the ____ for his saying "trick or treat".

A) conditioned stimulus
B) reinforcement
C) reward
D) discriminative stimulus