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#36954
Complete Question Explanation

Strengthen—CE. The correct answer choice is (B)

The conclusion of this stimulus is presented in the first sentence: Scientists hypothesize that P-fat is
necessary for eyesight development. This conclusion is based on the fact that babies that are fed milk
formulas that contain less P-fat have worse eyesight than those that are fed mother’s milk with high P-fat
content.

The scientists’ hypothesis is questionable, since other differences between formula and mother’s milk
might conceivably account for differences in eyesight development. Furthermore, the information could
be consistent with P-fat as a beneficial but unnecessary factor.

The inclusion of information about premature versus full-term babies can be confusing, because it does
not play an immediate role in the argument. In fact, this detail might make one wonder whether there is
simply a correlation between babies that are born prematurely and those likely to be fed formula, which
could mean that premature birth, rather than P-fat, is the cause.

Since we are asked to support the hypothesis, we should look for the choice which, if true, would make
it more likely that P-fat is indeed a necessity.

Answer choice (A): Since the stimulus concerns the development of eyesight, it is unclear how levels of
P-fat in adults is relevant.

Answer choice (B): This is the correct answer choice. If premature birth directly deprives the baby of
P-fat, it seems more likely that P-fat is the cause, rather than some other factor associated with premature
birth. This answer choice improves the argument, even if it doesn’t completely justify the conclusion.

Answer choice (C): This incorrect choice might be initially attractive, as it appears to eliminate genetics
as an alternate explanation, strengthening the conclusion. The argument in the stimulus, however, is that
P-fat is required, and ruling out other potential causes of poor eyesight would not affect the claim that
P-fat is necessary to eyesight development.

Answer choice (D): This answer choice is relevant only if we add the presumption that babies always
prefer substances that are more supportive of their eyesight development.

Answer choice (E): This answer choice does nothing to strengthen the scientists’ hypothesis that P-fat
is required for eyesight development. It may help to strengthen the link between premature birth to poor
eyesight, but that is not what we are looking for in response to this question.
 Arindom
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#25735
Hi,

According to the LR Bible, one way to strengthen a conclusion is to show that when the cause is present, the effect is present that is why I chose ans choice A that when the diet lacks P-fat, there is worse eyesight for adults.

So, why would this be incorrect?

Thanks.

- Arindom
 Nikki Siclunov
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#25954
Arindom,

You are correct in that examples where neither the cause, nor the effect, are found to occur generally strengthen a causal relationship between the cause and the effect. However, in this particular instance the argument posits a relationship between P-fat and the development of eyesight that is both causal and conditional. In conditional terms, P-fat is required for the development of eyesight (Eyesight development :arrow: P-fat). One can strengthen a conditional relationship by showing an instance of the contrapositive (no P-fat :arrow: poor Eyesight development). From a causal perspective (P-fat :arrow: Eyesight development), we can strengthen the argument in several different ways, including showing an instance where the cause does not occur, and the effect does not occur.

Unfortunately, answer choice (A) performs neither of these operations.

The argument is about eyesight development: whether P-fat is required for it or not. Such an argument can only be strengthened or weakened by examples involving infants, whose eyesight is still in development. Although adults' vision may deteriorate over time, the argument is not about whether P-fat protects one's vision against deterioration. It is that P-fat is required for proper eyesight development. Consequently, answer choice (A) introduces an irrelevant consideration.

The main gap in the reasoning here is between the second premise and the conclusion: what is the relevance of the observation that babies that are five to six weeks premature tend to have worse eyesight than babies carried to term? How does that strengthen the conclusion that P-fat is required for the development of eyesight? Well, if (B) is true, and a fetus receives high levels of P-fat from the mother during only the last four weeks of pregnancy, then no wonder babies that are born prematurely have worse eyesight: they never had the opportunity to benefit from the high levels of P-fat during the last four weeks of pregnancy. Abstractly put, answer choice (B) shows an example where the absence of the necessary condition results in the absence of the sufficient.

Hope this helps!

Thanks,
 AAron24!
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#78835
Can you explain 14? and How C does not strengthen the argument. I thought C would strengthen the argument as it is a defender answer choice? I get how B can be correct but am confused on why C is incorrect
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 Stephanie Turaj
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#78851
Hi AAron24!

I have moved your post to the thread discussing this question. Please review the above official explanation and the comments, and let us know if this helps. Thanks! :)

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