A student using a particular ball point pen gets an A on a final exam. From then on, she always uses that same pen whenever she takes a final. Which of the following is MOST similar to her behavior?

a. A dog that salivates at the sound of a bell that had originally been paired with the
presentation of food.
b. A rat that has learned to press on a bar in its cage that delivers a pellet of food.
c. A pigeon that hops around in circles on one foot until a grain of food is eventually
dropped in its cage.
d. A cat that presses a button in its cage, thus terminating an electric shock.

A