Little Tammy Is Frightened by Thunder and Cries When She

Multiple Choice

Little Tammy is frightened by thunder and cries when she hears it. During a season of frequent electrical storms, thunder is always preceded by lightning. Now Tammy cries as soon as she sees lightning. In this example, the conditioned stimulus is

A) lightning
B) crying at the sight of lightning.
C) thunder.
D) crying at the sound of thunder.