Final answer:
In this situation, the conditioned stimulus is the seeing boats.
Step-by-step explanation:
In this situation, the conditioned stimulus is the seeing boats. Gavin associates the sight of boats with feeling queasy because he became seasick while deep-sea fishing. The feeling queasy is the unconditioned response, as it is an involuntary physical reaction to being seasick initially. Deep-sea fishing and going with friends are not the conditioned stimulus in this scenario.