Katrina is trying to stop smoking. Her therapist suggests aversive conditioning, which pairs the cigarette with something unpleasant (like a nausea-inducing substance) to make the cigarette less appealing. In this case, the unconditioned stimulus would be:.

The nausea-inducing substance.

Explanation:

One of the examples of Aversion therapy is when someone is trying to stop smoking just like Katrina in the question above. That is to say when an individual or someone is trying to stop an habit that he or she is used to like before then we say that the person is going through an Aversion therapy.

Unconditioned stimulus has to deal with a stimuli(usually natural) that makes or causes another reaction for example now when someone puff air to another person's eyes, it will surely lead to that person's eyes to blink.

Hence, the nausea-inducing substance will be the Unconditioned stimulus which will trigger the "dislike response" so as for Katrina to stop smoking.

b) trade is easy because of the direct line between their major ports. bilateral trade reached 89,6 thousand million.