PrepTest 130, Section 1, Question 20
A person with a type B lipid profile(73 more words not shown)
If the information above is(10 more words not shown)
- AIn the experiment,(24 more words not shown)
- BPeople with type(17 more words not shown)
- CApart from adopting(26 more words not shown)
- DThe reduction in(15 more words not shown)
- EFor at least(21 more words not shown)
Reading the argument
Type B is associated with much greater heart-disease risk than type A. We can use that stated comparison without deciding why the difference exists.
When the volunteers adopt a low-fat diet, we might expect a health improvement. The actual results are mixed. The type B volunteers' cholesterol drops, but their profiles remain type B. The type A volunteers show no benefit, and forty percent move into the higher-risk type B category.
That last change is the connection to keep. At least some volunteers moved from the lower-risk profile to the higher-risk profile after beginning the diet. The result runs against the simple expectation that a low-fat diet would benefit everyone.
What we’re looking for
We're asked what must be true, so keep the claim within the information provided. We know the profile-associated risk and the change in profiles. We don't need to establish that the diet caused the change, or add a medical theory about cholesterol.
Working the answers
- A
The passage doesn't connect the type B volunteers' lower cholesterol with a reduction in their heart-disease risk. Nor are we given the sizes of the two groups to justify “most.” We cannot turn a reported cholesterol change into a risk reduction for a majority of volunteers.
- B
The first sentence compares the groups' heart-disease risk, not their cholesterol levels. We learn that cholesterol fell within the type B group, but not whether its average level was higher than type A's. A change within one group isn't the between-group comparison this choice asserts.
- C
Perhaps the experiment controlled other lifestyle changes, but the passage doesn't say so. We can't assume that most participants kept every relevant habit unchanged merely because the event is called an experiment.
- D
The reported cholesterol reduction occurred in the type B group, whose profiles did not change. The profile changes occurred among type A volunteers. Nothing establishes that reduced cholesterol was solely responsible for those changes; the claimed causal explanation goes beyond the evidence.
- ECorrect
Forty percent of the volunteers who began with type A profiles shifted to type B. Since a person with a type B profile is at much greater risk than a person with type A, at least some volunteers had increased risk after being put on the diet. The answer says “after,” preserving the observed sequence without requiring proof of the diet's causal role.
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