A large group of hyperactive children whose regular diets included food containing large amounts of additives was observed by researchers trained to assess the presence or absence of behavior problems. The children were then placed on a low-additive diet for several weeks, after which they were observed again. Originally nearly 60 percent of the children exhibited behavior problems; after the change in diet, only 30 percent did so. On the basis of these data, it can be concluded that food additives can contribute to behavior problems in hyperactive children.
The evidence cited fails to establish the conclusion because
(A) there is no evidence that the reduction in behavior problems was
proportionate to the reduction in food-additive intake - WRONG. 'Proportionality' ruins this option. Otherwise it was good.
(B) there is no way to know what changes would have occurred without the change of diet, since only children who changed to a low-additive diet were studied - CORRECT. Not 100% sure how this is right but it is. Hopefully the large group remained unchanged so this option confuses. Alternate cause is what i was looking for but none of the options offer that.
(C)
exactly how many children exhibited behavior problems after the change in diet cannot be determined, since the size of the group studied is not precisely given - WRONG. Knowing the number would not have helped us anyhow.
(D) there is no evidence that the
behavior of some of the children was unaffected by additives - WRONG. Yes, that's what passage also suggests. So nothing wrong as such in that.
(E) the evidence is
consistent with the claim that some children exhibit more frequent behavior problems after being on the low-additive diet than they had exhibited when first observed - WRONG. If it's consistent then how can it be flawed.
Answer A.
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