In the Context of Berkowitz' Studies of Aggression, 'Stimulus Pairing

In the context of Berkowitz' studies of aggression, 'stimulus pairing' refers to:

A) a generalized emotional reaction to aggression-related stimuli
B) a specific emotional response to pairs of aggressive stimuli
C) the activation of a series of aggression-related thoughts and feelings by a certain stimulus such as a gun
D) an increase in emotional response due to repeated exposure to aggression
E) a diversity of emotional responses which have been paired with particular stimuli