When Researchers Attempted to Teach Slugs to Dislike Foods by Pairing

When researchers attempted to teach slugs to dislike foods by pairing the food with an unpleasant taste, they found that:

A) slugs learned to avoid the smell of carrots, which they normally like, but attempts at higher-order conditioning failed.
B) after the smell of carrots was paired with the bitter-tasting drug, the slugs began to avoid the place where the association had been formed and would not eat any food in that context.
C) despite numerous procedures and many attempts, it was not possible to classically condition any responses in slugs.
D) slugs learned to avoid the smell of carrots and then, through higher-order conditioning pairing carrot smells and potato smells, slugs began to avoid the smell of potatoes.