SHSAHOO wrote:
GMATNinja, Could you please explain this it to me why A not C?
First, let's review the argument:
- In the lab, we had two groups of mice: Group A was fed reduced-calorie diets while Group B's caloric intake was not reduced. Group A lived longer, and some doctors concluded that reducing calories in human diets could increase human lifespans.
- But the dietary researcher disagrees: the researcher notes that Group A's "reduced" diet actually represented a natural/optimal diet for animals in their natural habitats and that Group A's "increased" life spans were actually just "normal" life spans.
- In other words, the researcher is pointing out that the study did NOT involve (1) mice eating a natural/optimal diet and (2) mice eating LESS than natural/optimal. Instead, it involved (1) mice eating a natural/optimal diet and (2) mice eating MORE than natural/optimal. So even though the study does suggest that eating MORE than natural/optimal is bad, it does NOT suggest that eating LESS than natural/optimal is good.
- So if humans are already eating a natural/optimal amount, there's no evidence that eating any less will increase their lifespans. Who knows, maybe it will actually be bad..?
There's an implied assumption in the logic, which is that humans are generally eating natural/optimal levels of food. If that is indeed the case, then the researcher is right: the study only tells us about natural/optimal vs. MORE than natural/optimal, so we shouldn't use it to draw conclusions about natural/optimal vs LESS than natural/optimal.
But what if humans are generally eating way more than natural/optimal levels of food? In that case, the study IS in fact relevant, and the doctors are justified in suggesting that we all reduce our caloric intake, to go from "above natural/optimal" down to "natural/optimal".
So (A) would support the doctors' advice and thus weaken the dietary researcher's argument.
As for (C): if this is true, then SOME scientific results that have important implications for human health are NOT based on studies of laboratory animals. Well, who cares? All sorts of other studies -- studies of plants, studies of humans themselves, studies of computer models, and so on -- could have important implications for human health. That doesn't mean that studies of laboratory animals are (or are not) useful, so this has no bearing on the dietary researcher's argument, or on the doctors' conclusion.
(A) is our winner.