Step-by-step explanation:
What is the unconditioned stimulus? Eating the oysters.
Art was naturally and automatically triggers in response to presence of food ( a stimulus)
What is the unconditioned response? Getting nauseous and feeling sick with an upset stomach.
What is the neutral stimulus that becomes the conditioned stimulus? Thought of oyster
After Art's experience, the thought of oyster is now the product of his learned behavior
What is the conditioned response? Feeling nauseated