TooLong150 wrote:
Source : GMATPrep Default Exam Pack
One of the limiting factors in human physical performance is the amount of oxygen that is absorbed by the muscles from the bloodstream. Accordingly, entrepreneurs have begun selling at gymnasiums and health clubs bottles of drinking water, labeled "SuperOXY," that has extra oxygen dissolved in the water. Such water would be useless in improving physical performance, however, since the amount of oxygen in the blood of people who are exercising is already more than the muscle can absorb.
The conclusion of this argument is that
SuperOXY would be useless in improving physical performance. Here's how the author reaches this conclusion:
- The amount of oxygen that muscles absorb from the bloodstream is a limiting factor in physical performance.
- SuperOXY is water with extra oxygen.
- Muscle can't absorb more oxygen than the amount that's already in the blood of people who are exercising.
- Therefore, SuperOXY won't do anything to improve physical performance.
This seems straightforward enough. Where this gets challenging is the question itself:
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Which of the following, if true, would serve the same function in the argument as the statement in boldface?
Whoa, let's unpack this for a second. This question forces us to think through a couple steps before we try to answer it:
1. What logical function does the boldface statement serve?
2. Which of the following choices, if true, serves that same logical function?
Before we move onto #2, let's make sure we have the right answer to #1.
The argument concludes that SuperOXY won't do anything to improve physical performance. The bolded statement tells us the reasoning behind this conclusion. More specifically, the bolded statement tells us that muscle can't absorb additional oxygen from the bloodstream.
This
supports the conclusion by confirming that
the oxygen in SuperOXY can't be absorbed by muscles. The correct answer choice will do both of these things! Now, let's start eliminating:
Quote:
(A) world-class athletes turn in record performance without such water
Who cares about record performances and world-class athletes? We're trying to support an argument about the effectiveness of SuperOXY. Choice (A) goes nowhere near that argument, so let's eliminate it.
Quote:
(B) frequent physical exercise increases the body’s ability to take in and use oxygen
Choice (B) doesn't get specific enough to tell us anything about how
muscle absorbs oxygen and doesn't imply anything about
SuperOXY. Eliminate (B).
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(C) the only way to get oxygen into the bloodstream so that it can be absorbed by the muscles is through the lungs
Bingo! (C) tells us that the
only way that oxygen can be
absorbed by muscles is
through the lungs. Ingesting water through your lungs would kill you! So choice (C) effectively tells us that SuperOXY can't be ingested in the only way that leads to more oxygen absorption.
This has nothing at all to do with
the amount of oxygen that can be absorbed through blood. But it doesn't have to, because we're asked if choice (C)
would serve the same function as the bolded statement. We're not adding (C) to the passage. Instead, we're replacing the bolded statement with (C). And it works in exactly the same way, supporting the conclusion by confirming that the oxygen in SuperOXY can't be absorbed by muscles. So let's keep it around.
Quote:
(D) lack of oxygen is not the only factor limiting human physical performance
So what? Choice (D) says absolutely nothing about SuperOXY, and the argument doesn't care at all about any of these other potential factors. We need a choice that supports the conclusion that SuperOXY won't increase oxygen absorption. (D) isn't that choice, so get rid of it.
Quote:
(E) the water lost in exercising can be replaced with ordinary tap water
Choice (E) doesn't even pretend to care about oxygen! And we certainly don't care about lost
water. So eliminate (E).
(C) is far and away the best choice. It might have been tough to see if we hadn't identified what exactly we were being asked to do. But once the question stem is cleared up, the process of elimination becomes as easy as... breathing water?
OK, maybe not that easy, but always take the time to know what argument you're dealing with and what question you need to answer. And definitely don't try to ingest water through your lungs. GMAC test centers really hate that.