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#8 - We can now dismiss the widely held suspicion that sugar

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Complete Question Explanation

Weaken. The correct answer choice is (C)

This stimulus discusses the impact of sugar consumption on hyperactivity in children with ADD (attention deficit disorder). The stimulus begins with the author’s conclusion: We can now dismiss the notion that sugar consumption exacerbates hyperactivity in ADD children. This conclusion is based on a “scientific study” (be wary of the vague appeal to authority here) which showed that hyperactivity levels among ADD children who were given three common sugars was not distinguishable from those of ADD children who received a sugar substitute (we should also note the vague description of the sugar substitute—its effects must be distinguishable from those of sugar for it to facilitate an effective control group).

The question stem asks which of the answer choices most weakens the argument.

Answer choice (A): The fact that only one of the sugars used in the study was widely suspected of exacerbating hyperactivity does not change the observed behavior of the study’s subjects. This does not weaken the conclusion drawn in the stimulus.

Answer choice (B): Since the stimulus is concerned exclusively with ADD children, information about children in general is not relevant to the argument.

Answer choice (C): This is the correct answer choice. If the sugar substitute used in the study had the same or similar effect as the three sugars, it would not facilitate a good control group for the study, and no conclusions about distinguishing characteristics of the sugars could be logically drawn.

Answer choice (D): As long as all groups participated in these activities, it would not affect the outcome of the study (of course if the control group participated in these activities but the sugar groups did not, the study would be severely flawed).

Answer choice (E): The fact that some children have this belief would not necessarily have an effect on this study, as it is unclear whether any of the subjects would have actually been able to make this distinction, nor whether such knowledge would have had any effects on their behavior.
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Hello - can someone further explain why D does not weaken the argument, or is irrelevant altogether? I think my general thought process was interpreting D as an alternative cause of hyperactivity. I now see that it wouldn't do much to conclusion, because it doesn't do much to explain how the study proves that sugar doesn't affect kids with ADD.
Adam Tyson
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If the entire study was done in circumstances that hype kids up, that might do some harm, because that might mask the effect of the sugar. However, just having some of the observations being made in those circumstances doesn't do much, because there may have been others, perhaps even the majority, in situations that were not conducive to hyperactivity. In those cases, if sugar caused hyperactivity and the substitute did not, we might expect the sugared kids to be more obviously hyper than the unsugared kids. I wouldn't say that it was irrelevant, but that it doesn't do much to hurt the argument.

The real problem with the study is that we can't be sure that the control group was a proper control group, as pointed out by answer C raises that possibility and introduces the biggest doubt about the validity of the study.
Adam M. Tyson
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