
Passage: For those who want to keep fit, the effect of alternating multiple physical exercises is better than that of a single project.A single project of exercise makes a small number of muscles developed, while the alternating multiple physical exercises can develop the body's muscle group in an all-round way, and the latter consumes more calories than the former.
Question: Which of the following options, if true, most advantageously reinforces the above argument?
A. A.In healthy people, the increase in health is directly proportional to the consumption of calories.
B. B.Fitness through athletic training is the most effective.
C. C.Those who have just recovered from a serious illness are not suitable for intense single physical exercise.
D. D.It is much more difficult to fully develop the muscle group of the human body than to promote the development of a small number of muscles.
Answer: