Task: Question Understanding
Input (English): Question: In an experiment, a scientist named Pavlov rang a bell before he fed his dogs, which made the dogs drool. Soon the dogs would drool when they heard the bell, even if they did not receive any food. What type of response did the dogs exhibit? (A) an instinct (B) an inherited trait (C) a learned behavior (D) a conscious behavior?
Output (English): Pavlov, bell, drool., dogs, drool, heard, receive, food., type, response, exhibit?