The idea that any perceivable neutral stimulus can serve as a conditioned stimulus (cs) was challenged by:

It was both John Garcia and Robert Koelling that challenged the idea that any perceivable neutral stimulus can serve as a conditioned stimulus.

Explanation:

Mr. Garcia and Mr. Koelling challenged the findings based on the rats taste aversion. They started their research in 1950 under several different conditions than researchers before them. One of the tests performed was rats given two bottles to drink from. The plastic bottle had been given right at the time the rats were exposed to radiation and the glass bottle did not. The rats drank only once from the bottle with the radiation and then only drank from the glass bottle, avoiding all contact with the plastic bottles.  It is believed the rats could still taste particles from the radiation.

answer; (b) binge eating disorder;