#23 - Global Reference, Must Be True

[Administrator]

This explanation is still in progress. Please post any questions below!

[June.K]

Hello,

I was split between answer choices A and E in this question. Can you please tell me why E is the best answer choice for this? In hindsight I can choose answer choice E through process of elimination, but am still not completely sure why it is the correct answer choice.

For answer choice A, I was originally confused on how detailed the answer needed to be to the posed question "what laboratory experiments were conducted by M&R in their research on CFCs?". For example, would it be fine to briefly explain (as the passage did) on how they observed the two freon gases slowly diffuse upward into the stratosphere and break down into constituent elements, including chlorine? I now see that this answer choice is most likely wrong because it mentions the word "laboratory experiments" and not "observations," but when I was going through the question under time pressure it wasn't as clear to me as it is now. Also, what if M&R had observed the break down of the two freon gases in a controlled lab environment, which accurately duplicated real life atmosphere conditions?

For answer choice E, I was originally doubtful largely because of the word "most" in the answer choice. Indeed, the passage states how "devastating" the effects of chlorine can be, but it never talks about any other of constituent elements. Most importantly, the passage does not mention (or imply from my reading of it) that chlorine is the 'most' damaging to ozone. What if there were a long list of constituent elements common to CFCs and the author was explaining how chlorine (one of the many harmful elements) can be devastating? The question stem implies that the answer choice can be proven through a Fact Test, but I wasn't able to prove any of the answer choices when taking the test.

I feel like the overall difficulty level for this question should be quite low in comparison to other questions in this particular RC section, but this was one of the two questions I got wrong in the section and I want to make sure I understand why the correct answer is correct.

Thanks in advance for your response. Besides the review I'm doing from taking preptests, this forum is an awesome tool that is helping me an immense amount!

Thanks!

[nicholaspavic]

Hi June,

Great question. You are definitely picking up on the right phrasing to disqualify Answer Option (A). Labaratory experiments are not specifically discussed. Rather sentences like this one imply that they were outside the lab: "Studying two freon gases—types of CFCs—they observed that, when released into the lower atmosphere (troposphere), these gases slowly diffuse upward into the stratosphere." Also, M&R may have observed the break down of the two freon gases in a controlled lab environment but we don't know that from the passage, so we cannot make that inference because it's just a guess.

Now turning to Answer (E), the word "most" seems to be the qualifier that turned you away from this answer. Certainly, the "devastating" description given helps support this answer, as you noted. But there's also additional support in the passage in the paragraph describing how "each chlorine atom could destroy as many as 100,000 ozone molecules before becoming inactive" and the way that CFC's can continue for many years (perhaps decades) to detroy the ozone, even after their initial release. Although the passage does not actuall use the word "most," those effects of the CFCs observed by M&R and described in the passage are also attributed to the subsequent action taken by the US government to ban CFCs. That action for the specified reasons given in the passage also support the interpretation that the chlorine (and other constituent elements) were the most damaging to the ozone.

Thanks for the great question and I hope this helped!

[June.K]

Hi Nicolas,

Thanks for your reply.

Although I'm still not 100% convinced with answer choice E, I guess I have to accept that this is the LSAT and questions that are superior to others are often the correct answer, no matter whether they can be proven 100%. Alas, what if there was a constituent element of CFC that had worse effects than those of chlorine that M&R observed, but were not specifically discussed in the passage? This is a possibility that opens up due to the author being silent as to whether chlorine was indeed the 'worst' of the constituent elements that could be derived from CFCs.

The acceptance of how certain answer choices could be correct regardless of the certainty factor actually helped me a lot in terms of timing as I would previously waste time in trying to prove the answer choice correct.

Again, thanks for your response. It was helpful nonetheless!

[Adam Tyson]

It's more of a negative implication, JuneK, in that the passage would probably have mentioned any constituent element that was worse than chlorine, if there was such an element. Otherwise why would they bother spending so much attention on chlorine and none on the other thing? Sure, it's possible, but it's unlikely, and E is a fine example of a "best" answer that may not be entirely perfect. Certainly after reading this passage, most people would be likely to say "chlorine" in response to E, while most of us would (or at least should) say "I don't know" in response to all the others.

You're right to focus on the superior, rather than the perfect. Good work!

[andreakun]

I was also thrown off by the "most" qualifier, but am starting to see why E makes the most sense out of all the answer choices. I just want to check my understanding. I initially chose D because, from this extract, i.e. "subjected to massive ultraviolet radiation, they break down into their constituent elements, including chlorine", I assumed that there are other constituent elements aside from chlorine contained in CFCs that contribute to ozone depletion. Therefore, other chemicals may share these other constituent elements.

Is the reason why D is wrong because it requires too much explanation to justify and other chemicals is not mentioned in the passage?

[KelseyWoods]

Hi Andrea!

You are correct that the line "they break down into their constituent elements, including chlorine" suggests that there are other constituent elements of CFCs. But it's too much of a leap to say that those elements also contribute to the destruction of ozone molecules. Based on what we know from the passage, the other elements could be completely harmless. It might only be chlorine that harms the ozone. Therefore, we don't really know whether other chemicals that share these other constituent elements, but not chlorine, would also contribute to ozone destruction.

Remember that the majority of RC questions are some form of Must Be True--you have to be able to prove the correct answer with the information in the passage. We can prove that there are other constituent elements of CFCs besides chlorine. We can prove that chlorine contributes to the destruction of the ozone. But we cannot prove that there are other chemicals which do not contain chlorine that also contribute to the destruction of ozone molecules.

Hope this helps!

Best,
Kelsey

[marioncarroll]

Confused by this answer since we know literally nothing about chlorine in relation to the other constituent elements. Why are we expected to assume that they mention chlorine because it is the most significant cause, when we are generally cautioned to never come to these conclusions based off of lack of evidence alone? Furthermore, it only mentions chlorine in one paragraph and then goes with the discussion about CFC's in general. This strengthens the potential impression that chlorine is listed specifically for reasons other than it being the "most damaging" constituent element. Perhaps chlorine was the most or only familiar term, so they listed it as an example over others for relatability purposes. The options are endless. This feels like it blatantly breaks the law of the LSAT land. I'd love to improve my understanding because surely I'm missing something.

[Jeff Wren]

Hi Marion,

Let's start with a key sentence in the passage.

"Molina and Rowland showed how manufactured chlorofluorocarbons (CFCs)—highly volatile
chemicals, millions of tons of which had been used each year in products such as aerosol sprays and refrigerants—chemically attack and deplete the ozone layer, diminishing its effectiveness as a shield against ultraviolet radiation." (lines 14-21).

This sentence establishes that what Molina and Rowland showed was actually how CFCs deplete the ozone layer. In other words, there's no reason to assume that Molina and Rowland got it wrong or missed some crucial piece of the puzzle, at least according to the passage.

What follows that sentence is a description of Molina and Rowland's observations that the CFCs break down into their constituent elements, including chlorine. Chlorine, and only chlorine, is described as being "devastating to the ozone layer" (line 28). The rest of the paragraph explains how/why chorine is so detrimental to the ozone layer. The passage isn't just mentioning chlorine as an example of the one of the elements causing depletion of the ozone layer, it is the thing causing the depletion of the ozone layer, due to the specific reasons described that are unique (as far as we know) to how chlorine interacts with ozone in a chain reaction.

While it is true that the impact on the ozone layer from other constituent elements is not discussed, the implication is that they are not significant. If they were, to neglect to mention them would have been a serious and problematic omission. Chlorine is the primary culprit here.

In other words, if one of the other constituent elements of CFCs (such as fluorine) was actually more damaging than chlorine, this passage really messed up the explanation, but there's no reason to think that.

Finally, while the passage does return to CFCs in the last paragraph, that is because it was the CFC containing products that were the problem in a broader sense and what needed to be banned, even though specifically it's the chlorine within the CFC that was the true culprit.

[marioncarroll]

Thank you for this thorough response! I have to admit I am still a bit unclear on this one. Just to clarify so I can remember when these question types appear, does the question type "the information in the passage most helps to answer which one of the following questions?" act as less of a must be true question and more of a 'is likely true' scenario? I think this would clear it up for me! Just because I totally understand that they really hammer down how detrimental chlorine is, but it's the answer language of being "most" damaging to the ozone without that being explicitly stated in the passage (but definitely strongly implied) that I'm struggling with. Thank you so much, I really appreciate your help!