Read the scenario below and answer the question that follows.Fred is playing the slot machines. After a certain number of plays, he wins a few coins, but Fred is unable to determine how many plays he needs to win. Which of the following statements is true?A.Fred is on a fixed-interval schedule of reinforcement.B.Fred is on a variable-interval schedule of reinforcement.C.Fred is on a fixed-ratio schedule of reinforcement.D.Fred is on a variable-ratio schedule of reinforcement.