After His Mother Smiles, Jimmy's Request for a Snack Is

Multiple Choice

After his mother smiles, Jimmy's request for a snack is reinforced. But if his mother is not smiling, his subsequent request for a snack is not reinforced. By indicating that Jimmy's request for a snack will be reinforced, the mother's smile is a

A) primary reinforcer.
B) discriminative stimulus.
C) respondent behavior.
D) unconditioned reinforcer.