In an attempt to debunk the myth that aggression is instinctual, biologist Zing Yang Kuo (1961) raised a kitten in the same cage with a rat. Not only did the cat refrain from killing the rat, but the two became quite close companions. This experiment demonstrated that

A) aggression is not instinctual.
B) the aggressive instinct can be inhibited by early experience.
C) it is possible to learn to discriminate—the cat would not attack rats, but would still attack other animals.
D) the aggressive instinct can be inhibited in an artificial environment.
E) the aggressive instinct can be inhibited in some species but not in others.

B) the aggressive instinct can be inhibited by early experience.