Physicians observe that an effective way to lower the risk of dementia is to eat three servings of vegetables every day. Studies have shown that the risk of dementia people who did so were significantly lower after six months than were those of people who did not, even though the risk of dementia of the two groups were the same before the studies began. Clearly, eating vegetables can have an appreciable effect on risk of dementia.

Physicians observe that an effective way to lower the risk of dementia is to eat three servings of vegetables every day. Studies have shown that the risk of dementia people who did so were significantly lower after six months than were those of people who did not, even though the risk of dementia of the two groups were the same before the studies began. Clearly, eating vegetables can have an appreciable effect on risk of dementia. 

The answer to which of the following questions, if true, would be most useful in evaluating the claim about vegetables above?

1. Is it realistic to expect people to eat three servings of vegetables per day?
2. Were the two groups of people in the study involved in the same exercise program?
3. Can the same drop in risk of dementia be achieved through medication?
4. Did the study continue to track the subjects beyond six months?
5. Are most people who are at risk of dementia aware of the difference between vegetables and grains?

OA: B

Question type: Evaluate

Difficulty level: Hard

Summary of the argument: eating vegetables is attributed to reduction in risk of dementia because of a study conducted on people who were at risk of dementia. 

1. Expectations are irrelevant since we are only concerned about the causative effect of eating vegetables and its effect on risk of dementia. 
2. This is relevant since it helps us evaluate the effects of an alternate cause – exercise. If exercise was a factor then it could question the strength of the link between vegetables and risk of dementia. 
3. Medication is out of score and irrelevant to the context of this argument. 
4. This while seeming relevant on the surface does not address the causal link. 
5. Difference between vegetables and grains is irrelevant.

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