Marvin happens to wear a red shirt when he takes a test he expects to fail. Surprisingly, he does well on the test, so he wears the red shirt every time he takes a test. Which of the following explains Marvin's superstitious behavior?
a. Learning sometimes becomes apparent when there is some incentive to demonstrate it.
b. Reinforcement for a task already enjoyed can backfire, reducing intrinsic motivation.
c. A continuous reinforcement schedule will lead to the most rapid learning.
d. Conditioned reinforcers get their power through learned association with primary reinforcers.
e. Any behavior that is accidentally reinforced is more likely to be repeated.