How did Kohn reach the conclusions that extrinsic rewards function as bribes?
a. Extrinsic rewards cause students to do academic work they would otherwise not do.
b. Extrinsic rewards ultimately make no difference on any kind of academic performance.
c. Extrinsic rewards only make a difference on behaviors that have no inherent reinforcement value.
d. All students naturally value intrinsic reinforcement more than extrinsic reinforcement.