Answer: the correct answer is A. In classical conditioning, the consequence arrives regardless of the animal's behavior, while, in operant conditioning, it only arrives once the animal has made a response.
Explanation:
Classical conditioning.(also known as Pavlovian or respondent conditioning) refers to a learning procedure in which a biologically potent stimulus (e.g. food) is paired with a previously neutral stimulus (e.g. a bell).
Operant conditioning is also a learning procedure but in this case the animal has to operate something ( e.g. a buttom) to obtain something.