Final answer:
Carl is demonstrating extrinsic motivation as he is motivated by an external reward, which in this case is the payment of $20 for mowing the yard. The correct answer to the student's question is: A. extrinsic.
Step-by-step explanation:
The student is asking about the type of motivation exhibited by Carl who mows the yard of his elderly neighbour each week for $20.
Extrinsic motivation is demonstrated when a person's behavior is driven by external rewards such as money, fame, grades, and praise. This type of motivation arises from outside the individual. In Carl's case, because he is being paid for his work, his motivation for mowing the yard is extrinsic.
On the other hand, intrinsic motivation comes from within the individual - when the behavior itself is rewarding or personally satisfying, regardless of any external outcome or reward.
The correct answer to the student's question is: A. extrinsic.