Answer:
external rewards; reduce any inherent intrinsic interest
Explanation:
External rewards are the rewards a person is given from an external source. This means that the person is motivated by a reward given by an external source.
Internal rewards are the rewards a person develops within themselves. This means that the person is motivated by something which they themseleves desire.
Here, reading for cash will only generate motivation to get the money. Without the money the children might not read. This means that their own interest towards reading will not be developed.