Cancer patients can develop an aversion to foods they eat right before undergoing chemotherapy. Although the foods themselves do not initially cause feelings of illness, pairing them with chemotherapy, which does cause patients to feel sick, leads to the foods becoming associated with these same feelings. This is an example of:

A) classical conditioning. C) the law of effect.

B) instrumental conditioning. D) extinction.

I'm going to say the answer is A. Means classical conditioning - Classical conditioning involves learning about the predictive relationship between some signal (CS) and the important event (US) that it predicts. When a signal such as the taste and smell of a particular food preceeds (and therefore seemingly predicts) the nauseating effects of chemotherapy (note that chemotherapeutic drugs naturally cause nausea), the patient begins to feel nauseated when they taste or smell the foods that they may have eaten just prior to their chemotherapy treatment. Because the food in question causes a conditioned nausea response, the patient often becomes averse to that particular food and understandably will avoid that food in the future! This conditioned "taste aversion" is a learned response (CR) acquired through experience.