Answer:
D. The more benefit they will receive from exercise.
Explanation:
When answering these types of questions, you want to go for the most logical answer. In this case, A and D sound great. Now look at them again... A says that the more intense the exercise needs to be. If you do more physical activities, you don't always have to intensify them if you don't want to. D says the more benefits they will receive from exercising. This seems more like the answer because you can actually get more benefits like being healthy, nice bod, etc. Hope this helps:)
