The sport of Tennis develops muscular strength, sharpens coordination and provides good cardiovascular exercise. However, it can strain joints especially in the knee, elbow and wrist area. Despite this drawback, tennis should be played by anyone attracted to it because of its possible benefits to physical health.

Which of the following, if true, most strengthen the author's conclusion?

A. Tennis is played on a variety of surfaces on outdoor courts or indoor sporting facilities.
B. The earnings of professional tennis players are the highest of any professional sport.
C. Damage to joints is extremely difficult to repair and may affect one's mobility for extended periods of time.
D. Tennis is a sport that is growing in many countries around the world.
E. Stretching exercises, warm-up, and professional consultation can prevent serious physical harm that can be caused by any sport.

















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[spoiler]Answer: E[/spoiler]
I understand the answer E, but I chose C. The reason is that the extreme difficulties of repairing the joints indicate how important the sport of tennis is, so people should play tennis to avoid damage of the joints. But indeed, answer C weakens the argument, can anyone explain to me?

Thanks,
Yvonne[/spoiler]