It's Difficult to Demonstrate That There Are Short-Range and Long-Range

Multiple Choice

It's difficult to demonstrate that there are short-range and long-range physical benefits for children as a result of their participation in sports programs. Why?

A) Because all children are active and physically fit.
B) Because sports may simply attract the children who were fittest in the first place.
C) Because only a very small percentage of children participate in sports.
D) Because sports aren't challenging enough to affect one's fitness level.
E) Because so many children are injured in sports.