The planarian was exposed to a puff of air multiple times and eventually did not react. this type of behavior is known as behavior.

Option B, learned

Explanation:

Learned behavior is caused when an organism has learned to behave in a certain manner when exposed to a particular condition again and again. This learned behavior becomes a part of his/her experiences.

Here ,the planarian has learned to "not react" when exposed to air puff multiple times.

Hence, option B is correct.