Rescorla (1966) trained dogs to avoid electric shock by jumping over a barrier. Groups of dogs were then presented with a tone in a positive, negative, or zero contingency with shock. The dogs exposed to the tone in a positive contingency with shock responded to that tone by

a. exhibiting conditioned suppression.
b. exhibiting disinhibition.
c. increasing their rate of jumping.
d. decreasing their rate of jumping.

Ans: c