Answer: B) An automatic set of motor habits.
Explanation: The Kerplunk experiment was a famous stimulus-response experiment conducted in rats. If the conditional rats were released into an alley or path that was very narrow, they ran in a straight line towardsthe end of the wall making a "kerplunk" sound. The first test found that they were going to run at full speed, leaving aside the food that had been moved closer. The shortening of the alley, and moving the food was a main sign that was ignored by the rats. In the longest alley, the rats ran normally until they reached their usual distance, the distance than the food normally was. They then stopped to sniff the area even when they had not reached the end of the alley, they often ignored the food that was farther away.
