LR Drill Set 9, Question 3
Research has shown that when the calorie consumption(95 more words not shown)
The argument depends on assuming(5 more words not shown)
- AResearchers have been(18 more words not shown)
- BA reduced-calorie diet(16 more words not shown)
- CLife spans exceeding(25 more words not shown)
- DAny change in(22 more words not shown)
- ERestricting calorie consumption(24 more words not shown)
Reading the argument
Living longer on average and breaking a species' longevity record are different results. We need to keep them separate here.
Suppose these animals normally live about a year, and the longest any has lived on a normal diet is five years. Reducing illness might raise the average to 1.2 years without producing a single animal that lives past five. Fewer animals die early, but the old record still stands.
The calorie-restricted group does something different: some animals live longer than any animal of that species has lived on a normal diet. In our example, those animals get past five years. That doesn't tell us the whole group's average lifespan. A few unusually long lives and a higher average aren't interchangeable.
Now look at the conclusion. The author calls the first result evidence that aging has slowed, but doesn't say that about the improvement from reducing illness. How did we move from years lived to the speed of aging? The study measures lifespan; the conclusion interprets what that measurement means.
What we’re looking for
The question asks for an assumption the argument needs. We don't have to invent a complete theory of aging. We need a connection the author relies on when treating these unusually long lives as evidence of slower aging. If a choice looks confusing, test whether the argument could still make that move without it.
Working the answers
- A
Researchers could have found differences in susceptibility to illness, and the author could still compare the two lifespan results. In fact, different animals might be more or less prone to getting sick. The argument doesn't require researchers to have been unable to detect those differences.
- B
The conclusion doesn't rank calorie restriction against every other way of increasing average lifespan. Exercise might do more, for example. Nor have we been told the calorie-restricted group's average increased. The evidence concerns some animals exceeding the old maximum, so this claim about the most effective way to improve the average goes well beyond what the reasoning needs.
- CCorrect
This supplies the link from exceeding the old maximum lifespan to slower aging. Without that link, the author has an interesting finding about how long certain animals lived but no stated basis for interpreting it as a change in their aging process.
Return to the first sentence if necessary: the calorie-restricted animals really do include animals that outlive the previous record on normal diets. C connects that result to the conclusion about those animals. It need not explain every part of the study by itself to state an assumption this part of the argument requires.
- D
This says that changing aging changes illness. The argument is trying to interpret the results of changing calorie intake or illness, using lifespan as the evidence. It doesn't need every change in aging to produce a change in illness. Those aren't the connection or direction the author relies on.
- E
This connects calorie restriction to illness. But the author can compare their effects on lifespan even if calorie restriction has no effect on how often animals get sick. Connecting the two interventions doesn't explain why exceeding the old lifespan record indicates slower aging. That's the missing connection C supplies.
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