Khalila decided to try a new dish consisting of rice and tomatoes just as she was coming down with the flu. Now, every time she sees rice or tomatoes, she gets sick to her stomach. In this example, Khalila's experience of nausea at the sight of rice or tomatoes exhibits a(n)

• A. unconditioned stimulus.
• B. unconditioned response.
• C. conditioned stimulus.
• D. conditioned response.