PrepTest 130, Section 3, Question 11
Scientists have long thought that omega-3 fatty acids(65 more words not shown)
Which one of the following(7 more words not shown)
- AThe test subjects(12 more words not shown)
- BThe test subjects(25 more words not shown)
- CThe test subjects(28 more words not shown)
- DThe test subjects(30 more words not shown)
- EThe test subjects(23 more words not shown)
Reading the argument
People who eat fish twice a week have less heart disease. Is the fish making the difference, or do those people differ in some other important way?
Perhaps they have higher incomes and better access to medical care. Perhaps where they live is associated with some other habit that helps their health. The study gives us an association between eating fish and a lower risk; it doesn't automatically isolate fish as the explanation.
The scientists hold two related views: omega-3 fatty acids in fish oil lower cholesterol, and a modest amount of fish provides substantial health benefits. The author presents this study as strong support for both.
What we’re looking for
For the required assumption, focus on what would undermine that use of the study. A competing explanation for the fish eaters' lower heart-disease rate could account for the result without a benefit from fish. I'd expect an assumption protecting against that possibility, rather than simply another fact about the subjects' lifestyles.
Working the answers
- A
The non-fish eaters could be vegetarians. That label alone doesn't show that they have some independent reason for a higher heart-disease rate. The argument doesn't require excluding every vegetarian from the comparison; it needs to avoid a relevant difference that explains the observed advantage without fish. We aren't given the connection that would make vegetarianism such an explanation.
- B
The fish eaters' remaining diet needn't be entirely free of features conducive to heart disease. Imagine both groups otherwise eat the same diet of cheeseburgers and fries, but one group also eats fish. Comparing those groups could still provide evidence about fish. What matters is the relevant comparison, not a guarantee that the fish eaters have no other dietary risks.
- C
The author doesn't need non-fish eaters to consume significantly more red meat. They could consume the same amount. In fact, if a difference in red-meat consumption explained the difference in disease rates, it would give us an alternative to the author's explanation rather than something the argument needs to assume.
- DCorrect
'Augment cardiorespiratory health' means improve the health of the heart and respiratory system. Suppose the fish eaters were significantly more likely to exercise regularly in ways known to provide that benefit. Their lower disease rate could reflect those activities rather than the fish. The argument relies on the absence of this significant competing advantage when presenting the study as strong support for the fish-related health claims.
- E
Watch the direction. This rules out the fish eaters being more likely to have sedentary jobs. But if such jobs were a health disadvantage, more of them among the fish eaters would not explain why the fish eaters had less heart disease. They could have that disadvantage and still benefit from fish. D rules out a competing healthy behavior among the healthier group; E rules out a possible disadvantage. The argument does not require E, and 'no more likely' also rules out even a trivial difference that needn't affect the comparison.
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