Answer:
The answer is 1. classical conditioning.
Step-by-step explanation:
Classical conditioning refers to the association of a conditioned stimulus (the alcohol in this case) with an unconditioned stimulus (the pain produced by the vaccinations), thus provoking an conditioned response (fear).
Russian scientist Ivan Pavlov is famous for his research on classical conditioning. In one experiment, he would ring a bell every time he was going to feed a dog. Soon, the dog started salivating at the sound of the bell.