For several weeks, allen had to clean the men's restroom at the restaurant where he worked. the task always made him nauseated. he has since gone on to better things, but still cannot walk by the door to a men's restroom without becoming slightly queasy. for allen, the door to the men's room has become a(n)

For Allen, the door to the men's room has become a "conditioned stimulus".

In classical conditioning, the conditioned stimulus refers to a formerly neutral stimulus that, which becomes conditioned stimulus when it is associated or linked to the unconditioned stimulus.

This is also known in Pavlov's Classical conditioning, Ivan Pavlov was the one who first found the procedure of classical conditioning in his experiments.

answer; ///approx///5,000 miles;