Sometimes Leslie Is Terrified of Spiders; Sometimes She Is Not

Sometimes Leslie is terrified of spiders; sometimes she is not. According to Dollard and Miller, one likely reason for this variation in the level of fear is

A) whether Leslie has actually ever been bitten by a spider.
B) how far away the spider is.
C) whether Leslie is alone or with other people.
D) how long it has been since Leslie has eaten.