One of the limiting factors in human physical performance is the amoun

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:


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:


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.


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).


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.


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.


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.