People with higher-than-average

Answer choices

1. A

   No Impact13% picked this

   Many Alzheimer's patients have normal homoocysteine

   This is a very weak claim saying that "at least 5 people with Alzheimer's have normal homocysteine". Okay ... was the author assuming that all Alzheimer's patients had abnormal homocysteine levels? No, so this has no impact. Whenever arguments are based on correlations (such as "people who are X are twice as likely to be Y"), we can't weaken that by pointing out that some exceptions exist (by saying "Some X's aren't Y").

   13%
2. B

   Out of Scope: not-Alzheimer's5% picked this

   The substances into which homocysteine is converted can sometimes have harmful effects unrelated

   This argument is only about whether adding certain things to our diet could reduce the incidence of Alzheimer's disease, so whatever other effects homocysteine might have that are unrelated to Alzheimer's wouldn't be relevant to this conversation.

   5%
3. C

   No Impact9% picked this

   B vitamins and folic acid are not metabolized by the body very efficiently when taken in the

   This would only weaken if the author had suggested that we all start ingesting large amounts of folic acid and B vitamins -- this is saying that ingesting them via supplements probably wouldn't work very well.. This really has nothing to do with the argument; the author never said that ingesting large amounts via supplements would lead to a reduction in Alzheimer's.

   9%
4. D

   Weak Impact7% picked this

   People whose relatives contracted Alzheimer's disease are much more likely to develop Alzheimer's than those

   This answer suggests that whether people get Alzheimer's has a lot to do with genetics (since it seems to "run in the family"). The author is thinking that our risk of Alzheimer's has a big environmental influence (since she is thinking that by altering our diet we could reduce our risk). So the more we think that Alzheimer's is genetically, not environmentally, determined, the worse this argument looks. But this answer still has limited impact. It isn't allowing us to assume that Alzheimer's is completely genetically determined. A lot of diseases have genetic and environmental components to it. A person from a family with a history of lung disease is at a higher risk of lung cancer, but they can still increase their risk even more by smoking cigarettes. So this answer suggests there may be a genetic component to developing Alzheimer's, but it doesn't do anything to reduce the idea that there could also be an environmental, dietary component as well.

   7%
5. E

   Correct67% picked this

   Alzheimer's disease tends to increase the levels of homocysteine in

   Why this is right

   This suggests an alternate explanation for the correlation in the first sentence. It's not that higher homocysteine is causing the Alzheimer's; having Alzheimer's is causing the higher homocysteine. Whenever we see a correlation between X and Y that the author interprets to mean "X causes Y", we want to consider the alternate explanations of Reverse Causality (Y causes X) and 3rd Factor (Z causes X and Y). This answer is just doing the classic Reverse Causality alternate explanation. Once we realize that high homocysteine is an effect of Alzheimer's, not a cause of it, it weakens the conclusion that eating stuff in order to lower your homocysteine would lower your risk of Alzheimer's.

   Skill tested: Weaken · how this choice captures the argument's function is the move to repeat next time.

   67%