"Carson used to enjoy lime sherbet so when he was in Mexico, he tried frozen lime margaritas. After his fourth margarita, Carson became extremely ill. Now he finds that even the sight of lime sherbet in a bowl can make him feel queasy. In this example, the unconditioned stimulus is"

The lime margaritas that Carson consumed.  

Explanation:

Unconditioned stimulus: It is part of classical conditioning. In classical conditioning, a person or animal learn through conditioning. Classical conditioning, that had a great impact on the learning of an animal. There are four types of stimulus:

The unconditioned stimulus: This is the stimulus that trig-erred the response without conditioning. The conditioning occurs naturally. It automatically triggers the response. For instance: Carson fell ill because of the smell of the lime sherbet sight even he does not drink now. But it occurs naturally. This is an example of an unconditioned stimulus.