#26 - Concept Reference, Must Be True

[Adam Tyson]

Stick with the info from the passage, RajPatel, and not any outside info. Here, the author told us that the lower atmosphere is the troposphere, and that CFCs released there drift upwards into the stratosphere, where they have those problematic reactions. If we were looking for a replacement for CFCs, what good would it do us to look at how it behaves in the lower atmosphere? And what is this bit about chemicals "commonly found" there? Do CFCs have something to do with chemicals commonly found somewhere? Don't we want to know whether those chemicals would drift upwards, like CFC does, and what they would do up in the stratosphere? Would they release chlorine, or something like chlorine, that would damage the ozone layer? Also, is "reacting" by itself a problem, or is it only certain types of reactions that matter?

Your goal in this question is to select an answer that asks a crucial question, one that will help us better analyze a potential replacement for CFCs. This is a lot like an Evaluate the Argument question in LR, where you have to find the answer that asks the right question.

Try a thought experiment here: imagine that we are testing a potential replacement for CFCs. Let's say we are testing XYZs to see if they will do the job. Now imagine that we conduct a test to see whether XYZs react with chemicals commonly found in the lower atmosphere. What are the possible outcomes? It's either "yes, they do react" or "no, they do not react." What impact would a Yes have on our analysis? Would that mean they are not an acceptable replacement? What if the answer is No, they do not react - would that mean they are okay as a replacement? I think in either case we would be left unsure, because we wouldn't know what might happen to the ozone as a result of any of that. Are those reactions good for it, bad for it, or neutral? Would XYZs even interact with the ozone?

Since answer B doesn't ask a particularly crucial question, and answer D asks one that is more salient, answer B is not the most useful question to ask. It's not wrong to ask it, but it's just not as important to ask as answer D is. If XYZs contain parts that are similar to chlorine, the main culprit in the destruction of the ozone, that would be very useful to know. It wouldn't tell us for sure whether they are an acceptable replacement or not, but at least we would have some valuable information that would help in making that determination.

Answer B isn't a wrong answer - it's just not the best answer, and we always want the one that is best. Don't just look at answer B in isolation, but compare it to answer D. What makes one of them more useful than the other? Don't just go for an answer that could work, or that might be okay. Go for the one that is better than the other four choices!