When Bill was a kid, he would always get motion sickness in the car. He felt nauseous and sometimes threw up. Whenever his mom was driving, she would eat cinnamon Altoids. Even as an adult, the smell of cinnamon Altoids makes Bill feel nauseous and queasy.
Feeling nauseous when Bill smells Altoids as an adult is:
A. Conditioned stimulus
B. Unconditioned stimulus
C. Conditioned response
D. Unconditioned response