Answer: Classical conditioning.
Explanation:
Classical conditioning is defined as process in which association or link between potent stimulus and earlier unbiased stimulus is established for generation of learned response. This mechanism induces involuntary responses in humans or animals.
According to the question, Shannon's behavior of getting scared if she hears rustling sound from woods while walking because of her past interaction with bear while nature walk.This induces a learned response through link of rustling sound with fear through classical conditioning.