The correct answer is that certain stimuli are easier to associate than others because of biological preparedness
Conditioned taste aversion is a conditioned response in which the person / animal establishes an association" between having ingested a food and feel sick posteriorly. The association results from a single experience (unpleasant) and lasts the life all.
Aversion occurs even if the person knows that the disease was due to a virus, nothing having to do with food. No matter, the body rushes to the conclusion of that the food it is bad, and this becomes repulsive from then on.
The heart (or the stomach) overcomes the brain, and food innocent disgusts us. This illustrates how the aversion to flavors involves automatic, involuntary and primitive processes of our brain.