Frank once ate an orange and shortly afterwards he got the flu. although the orange did not cause frank to become ill, he no longer likes to eat oranges. what is the conditioned stimulus?

In this scenario the conditioned stimulus is eating oranges will cause Frank to become ill. This scenario is an aspect of the process of classical conditioning. The conditioned stimulus is some neutral object or action that has become associated with an unconditioned stimulus. The new association will now trigger a conditioned response.