Section: Logical Reasoning

34) Nutritionist:Recent studies show that the height of the average American has increased 2 inches in the past 10 years, lending support to the view that modern foods stimulate growth.

This argument would be weakened most by pointing out that

1. statistics don't lie
2. there are too many variables in this type of study
3. the generic background of the subjects was not investigated
4. the sample group used was small
5. some people's height decreased

Pointing out that "there are too many variables in this type of study" weakens the argument tremendously, because isolating the reason for the growth increase now becomes very difficult. Thus, we could not deduce that modern foods stimulate growth. (D) is close, as it also weakens the argument, but it isn't specific enough. If (D) were "too small," then it would be an excellent answer.