单选题 A researcher found that, in proportion to their body weights, children eat more carbohydrates than adults do. Children also exercise more than adults do. The researcher hypothesized that carbohydrate consumption varies in direct proportion to the calorie demands associated with different levels of exercise.
Which of the following, if true, most seriously undermines the researcher's hypothesis?

A、 More carbohydrates are eaten per capita in nations where the government spends more per capita on public exercise programs.
B、 Children who do not participate in organized sports tend to eat fewer carbohydrates than children who participate in organized sports.
C、 Consumption of increased amounts of carbohydrates is a popular tactic of runners preparing for long-distance races.
D、 Periods of physical growth require a relatively higher level of carbohydrate consumption than otherwise.
E、 (E) Though carbohydrates are necessary for the maintenance of good health, people who consume more carbohydrates are not necessarily healthier.

【正确答案】 D

【答案解析】[解析] 本题属于一个典型的由一个discovery得到一个结论，属于“B，A”型，反对的思路多为“有其他原因来解释B”。(D)正确，因为它指出除了运动因素以外还有身体生长因素影响碳水化合物的服用量。