Answer:
Aaron's attitude toward the task exemplifies A. the insufficient justification effect.
Explanation:
The insufficient justification effect tries to offer an explanation to why individuals facing cognitive dissonance still deal with the situation causing the dissonance. Cognitive dissonance happens when individuals find themselves in conflict. Maybe they believe in something but are forced to see that belief as incorrect, for instance. That will cause a discomfort - dissonance - that will only go away when the person involved changes something about the situation or their beliefs.
One way to make cognitive dissonance go away is by finding an internal explanation to something when the external explanation is clearly insufficient. That is what Aaron has done. There is no reason for his brother to make more money than he does for doing the same task. Aaron, however, has overcome the discomfort caused by the situation. He might have decided, for example, that he is not doing it for the money, that the task is fun, or that it feels nice to help. He has found an interior justification - the insufficient justification effect.