Read the scenario below and answer the question that follows.Harrison sends an e-mail to his boss. Harrison expects a response within five minutes, but he can’t help himself and checks every 30 seconds. After five minutes, a replying e-mail is delivered just as he expected.Which of the following statements is true?A.Harrison is on a fixed-interval schedule of reinforcement.B.Harrison is on a variable-interval schedule of reinforcement.C.Harrison is on a fixed-ratio schedule of reinforcement.D.Harrison is on a variable-ratio schedule of reinforcement.