#21 - People with higher-than-average blood levels of a

[ericj_williams]

Could you help me understand why D would be incorrect if seen as an alternate cause?

D seems to imply it is actually genetic vs caused by homocysteine. At least that's how I saw it.

Re-reading I can see that D a little more "off-topic" that E, which contains two key terms of the stimulus.

[Meshal Alotaibi]

Hi, the conclusion has risk of "developing" language, why would E be relevant if the disease exists, or is that a wrong interpretation option E? In other words, assuming that the disease is not there, the higher-than-average level would indicate that the risk of development is high, and the author argues that reducing the levels of H would help in reducing the risk of the disease. Option E instead is saying that the disease increases it, but that's besides in the point. I choose option B even those its language is weak in that it uses "can... sometimes." Thanks

[Luke Haqq]

Hi Meshal!

This stimulus identifies a specific causal relationship. It indicates that homocysteine is the cause and the effect is Alzheimer's disease.

In general, there are several ways to weaken cause and effect claims. For example, one could show the existence of the cause without it leading to the effect, or show that the cause and effect relationship is instead reversed. Answer choice (E) does the latter; rather than homocysteine causing Alzheimer's, it suggests that the cause and effect relationship is reversed, with Alzheimer's causing homocysteine levels to rise.

Answer choice (B) doesn't get to the conclusion. The conclusion is that "it is likely that the risk of developing Alzheimer’s disease could be reduced"--the risk in the conclusion is just about Alzheimer's disease and nothing else. Even if the mentioned conversion process had other harmful effects, it could still reduce the risk of developing Alzheimer's.