The correct answer is classical conditioning.
Classical conditioning refers to the behavioral process whereby, a neutral stimulus being paired with a unconditioned stimulus, is able and sufficient to elicit a response in an individual, even in the absence of the unconditioned stimulus. In this instance, the unconditioned stimulus (UCS) is the negative experience of being cold, the conditioned stimulus is Hal's presence and the response is dislike and negative feelings. Peter did not like Hal much because the thought or presence of Hal alone made him experience feelings or dislike and distaste.