狒狒114题，感觉答案有问题

114. The number of North American children who are obese-that is, who have more body fat than do 85 percent of North American children their age---is steadily increasing, according to four major studies conducted over the past 15 years.

If the finding reported above is correct, it can be properly concluded that

A.       when four majors studies all produce similar results, those studies must be accurate

B.        North American children have been progressively less physically active over the past 15 years

C.        the number of North American children who are not obese increased over the past 15 years

D.       over the past 15 years, the number of North American children who are underweight has declined

E.        the incidence of obesity in North American children tends to increase as the children grow older

答案给的C， 还有一堆解释。

麻烦大家看看E，稍微算一下就知道对。%升，一个尚未有obesity的child第二年tend to obesity的几率也升。