In 1994, a team of scientists led by David McKay began studying the meteorite ALH84001, which had been discovered in Antarctica in 1984. Two years later, the McKay team announced that ALH84001, which scientists generally agree originated on Mars, contained compelling evidence that life once existed on Mars. This evidence includes the discovery of organic molecules in ALH84001, the first ever found in Martian rock. Organic molecules—complex, carbon-based compounds— form the basis for terrestrial life. The organic molecules found in ALH84001 are poly cyclic aromatic hydrocarbons, or PAHs. When microbes die, their organic material often decays into PAHs. Skepticism about the McKay team’s claim remains, however. For example, ALH84001 has been on Earth for 13,000 years, suggesting to some scientists that its PAHs might have resulted from terrestrial contamination. However, McKay’s team has demonstrated that the concentration of PAHs increases as one looks deeper into ALH84001, contrary to what one would expect from terrestrial contamination. The skeptics’ strongest argument, however, is that processes unrelated to organic life can easily produce all the evidence found by McKay’s team, including PAHs. For example, star formation produces PAHs. Moreover, PAHs frequently appear in other meteorites, and no one attributes their presence to life processes. Yet McKay’s team notes that the particular combination of PAHs in ALH84001 is more similar to the combinations produced by decaying organisms than to those originating from non biological processes. 1 1. The primary purpose of the passage is to: (A) describe new ways of studying the possibility that life once existed on Mars (B) revise a theory regarding the existence of life on Mars in light of new evidence (C) reconcile conflicting viewpoints regarding the possibility that life once existed on Mars (D) evaluate a recently proposed argument concerning the origin of ALH84001 (E) describe a controversy concerning the significance of evidence from ALH84001 2 2. The passage asserts which of the following about the claim that ALH84001 originated on Mars? (A) It was initially proposed by the McKay team of scientists. (B) It is not a matter of widespread scientific dispute. (C) It has been questioned by some skeptics of the McKay team’s work. (D) It has been undermined by recent work on PAHs. (E) It is incompatible with the fact that ALH84001 has been on Earth for 13,000 years. 3 3. The passage suggests that the fact that ALH84001 has been on Earth for 13,000 years has been used by some scientists to support which of the following claims about ALH84001? (A) ALH84001 may not have originated on Mars. (B) ALH84001 contains PAHs that are the result of nonbiological processes. (C) ALH84001 may not have contained PAHs when it landed on Earth. (D) The organic molecules found in ALH84001 are not PAHs. (E) The organic molecules found in ALH84001 could not be the result of terrestrial contamination. 4 4. The passage suggests that if a meteorite contained PAHs that were the result of terrestrial contamination, then one would expect which of the following to be true? (A) The meteorite would have been on Earth for more than 13,000 years. (B) The meteorite would have originated from a source other than Mars. (C) The PAHs contained in the meteorite would have originated from nonbiological processes. (D) The meteorite would contain fewer PAHs than most other meteorites contain. (E) The PAHs contained in the meteorite would be concentrated toward the meteorite’s surface. 5 5. Which of the following best describes the function of the last sentence of the first paragraph? (A) It identifies a possible organic source for the PAHs found in ALH84001. (B) It describes a feature of PAHs that is not shared by other types of organic molecules. (C) It explains how a characteristic common to most meteorites originates. (D) It suggests how the terrestrial contamination of ALH84001 might have taken place. (E) It presents evidence that undermines the claim that life once existed on Mars. 6 6. The passage suggests that McKay’s team would agree with which of the following regarding the PAHs produced by non organic processes? (A) These PAHs are not likely to be found in any meteorite that has been on Earth for 13,000 years or more. (B) These PAHs are not likely to be found in any meteorite that originated from Mars. (C) These PAHs are not likely to be produced by star formation. (D) These PAHs are likely to be found in combinations that distinguish them from the PAHs produced by organic processes. (E) These PAHs are likely to be found in fewer meteorites than the PAHs produced by organic processes.

Question 6 (B) and (D) for this question aren't really "close" to one another, unfortunately. Here's a general rant about what might be happening when you're stuck between two answer choices: It's not that uncommon to be stuck between two answer choices -- after all, it could be that the person who wrote the question only had one great idea for a "tempting" incorrect answer choice. Unfortunately, a near-miss is still a miss on the GMAT. “Close” might be a great result if you’re playing shuffleboard, horseshoes, or Russian roulette, but it doesn’t mean anything on a multiple choice test. You're not necessarily close to a score breakthrough just because you’ve narrowed your critical reasoning or reading comprehension questions down to the last two options. If you miss a GMAT CR or RC question, it’s probably because you misread or misinterpreted something, either in the answer choices or in the passage itself. Even if you feel like you’re “close” on the majority of your misses, stay focused on the fundamentals : read with laser-like precision, practice hard using official GMAT and LSAT questions, and concentrate on honing your ability to distinguish between similar-sounding answer choices. Eventually, you can get substantially better at catching the nuances of GMAT verbal passages, questions, and answer choices. On the majority of GMAT verbal questions, you’ll still be forced into a difficult choice between the last two answers. But as you strengthen your ability to understand the phrasing and logic behind CR and RC questions, you’ll choose the correct option more and more frequently. -------------- Rant over, now back to the question at hand: to answer question 6, we need to find which answer choice McKay's team would agree with. McKay's team thinks that this particular meteorite contains evidence of life on Mars. In the second paragraph, the author presents some points from people who are skeptical of this claim, and then shows how McKay would respond to these points: Skeptical point #1: Maybe the meteorite just got contaminated by PAHs from earth. McKay response: There are more PAH's deeper in the rock than on the surface Skeptical point #2: PAHs can be produced by non-organic processes McKay's response: the particular combination of PAHs in ALH84001 is more similar to the combinations produced by decaying organisms than to those originating from non biological processes. Question #6 asks particularly about the PAHs mentioned in skeptical point #2. What would McKay's team think about these non-organic PAHs? There's no evidence that McKay's team would agree with this. McKay says that the particular combination of PAHs in this specific meteorite seem organic in origin. He never argues that non-organic PAHs wouldn't be found in ANY rocks coming from Mars. Sure, McKay is trying to convince the skeptics that the meteorite contains evidence of life on Mars. But there's no indication in the passage that McKay would bury his head in the sand and deny that non-organic PAHs exist on Mars. Instead, he takes the much more reasonable stance that the particular PAHs in this particular meteorite are more likely to be organic in nature. There's no evidence that McKay's team would agree with (B), so eliminate this answer choice. A note on extreme language: it is definitely important to notice extreme language in an answer choice -- here, the word "any" makes (B) a very strong statement. However, the mere presence of extreme language isn't enough to make a decision (there are plenty of correct answers that contain strong language). Instead, just think about how those key words impact the meaning of the answer choice as a whole, and then use this assessment when considering whether you can eliminate that answer choice. Does this merely regurgitate info from the passage? Yeah, kind of (although not explicitly). Is that a deal breaker? Not at all! We're just trying to find a statement that McKay would agree with, and he would definitely agree with (D). McKay argues that the combination of PAHs in the meteorite indicates that they originated from an organic source. So, he would agree that non -organic PAHs are likely to be found in combinations that can be distinguished from organic PAHs. McKay's team would agree with (D), so (D) is the correct answer to question 6. I hope that helps!

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In 1994, a team of scientists led by David McKay began studying

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Laksh47

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29 Dec 2020, 03:35

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Could someone please explain why option C of Question 1 is incorrect?

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17 Feb 2021, 23:53

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Hi Experts,
Can you please explain what is wrong with Option D in question 5 ?
Passage says "This evidence includes the discovery of organic molecules in ALH84001, the first ever found in Martian rock. Organic molecules-complex, carbon-based compounds-form the basis for terrestrial life. The organic molecules found in ALH84001 are poly cyclic aromatic hydrocarbons, or PAHs. When microbes die, their organic material often decays into PAHs"
Choice D -> It suggests how the terrestrial contamination of ALH84001 might have taken place.
As per above(highlighted in bold), When microbes die, their organic material often decays into PAHs and Organic molecules form the basis for terrestrial life.

What is wrong with choice D, What am I missing ?

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18 Feb 2021, 04:48

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vishuvashishth

Hi

The meaning of the word "terrestrial" in this context refers to the surface of the land on earth. In other words, when skeptics argue that the PAHs might be caused due to "terrestrial contamination", they are saying the PAHs could have reached the rock on earth instead of on Mars.

Option (D) states: It suggests how the terrestrial contamination of ALH84001 might have taken place.

Therefore, the last sentence must explain how the PAHs could have reached the surface of the rock on earth as opposed to on Mars. Clearly, the last sentence of the first paragraph does not explain this, and hence option (D) is incorrect.

Hope this helps.

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GMATNinja, went through your fantastic no retakes class on RC topics don't matter - Science Passages just a while back. Despite the clarity with which I understood the passage through your brief notes and apt explanation, I found myself utterly confused between option B and D in Question 6 and spent about 4 minutes to get the ans right. Specifically I have the following questions with regard to B and D:
- Doesn't D look like almost regurgitating from the passage?
- Team McKay's objective was to prove existence of life in Mars through PAHs so why wouldn't they agree to B?
- Are the options close or was I hallucinating?
- Is extreme langauge a solid reason to eliminate such close options? Sometimes being to focused on modifiers and extreme language in option seems akin to "awkward" and wordy grounds on SC which I totally agree with you aren't solid grounds for elimination. So should I eliminate options on those grounds?
- A more general question: I do always get into this trap of last 2 options and inevitably mark the one that isn't the ans. Other than comprehending well both passage and options is there any approach that I could use?
Curious to know what are your thoughts. Thanks again Charles

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23 Jun 2021, 21:24

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Jainam24

Jainam24, I understand that you're query is for Gmatninja, but I'm sharing my thoughts on question 6. See if it helps whilst you wait for his reply.

Option B has a lot of similar terminology, but has absolutely nothing to do with the answer or even to the passage. The option is not wrong because it's extreme, but because it states something that is not given in the passage. Team Mckay's point is that that the particular combination of PAHs in ALH84001 is more similar to the combinations produced by decaying organisms than to those originating from non biological processes (If X is more similar to A than it is to B, there must be some difference between A and B). Yeah sure, option B probably helps team Mckay's goal, but the team wouldn't agree to just because it supports the team's goals. There is no scientific backing (or backing of any kind) to what option B is saying, at least not in the passage.

I'm not an expert so I'll refrain from commenting on the general queries about trap answers.

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26 Jun 2021, 08:32

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Question 6

Jainam24

(B) and (D) for this question aren't really "close" to one another, unfortunately. Here's a general rant about what might be happening when you're stuck between two answer choices:

It's not that uncommon to be stuck between two answer choices -- after all, it could be that the person who wrote the question only had one great idea for a "tempting" incorrect answer choice.

Unfortunately, a near-miss is still a miss on the GMAT. “Close” might be a great result if you’re playing shuffleboard, horseshoes, or Russian roulette, but it doesn’t mean anything on a multiple choice test. You're not necessarily close to a score breakthrough just because you’ve narrowed your critical reasoning or reading comprehension questions down to the last two options.

If you miss a GMAT CR or RC question, it’s probably because you misread or misinterpreted something, either in the answer choices or in the passage itself. Even if you feel like you’re “close” on the majority of your misses, stay focused on the fundamentals: read with laser-like precision, practice hard using official GMAT and LSAT questions, and concentrate on honing your ability to distinguish between similar-sounding answer choices.

Eventually, you can get substantially better at catching the nuances of GMAT verbal passages, questions, and answer choices. On the majority of GMAT verbal questions, you’ll still be forced into a difficult choice between the last two answers. But as you strengthen your ability to understand the phrasing and logic behind CR and RC questions, you’ll choose the correct option more and more frequently.

--------------

Rant over, now back to the question at hand: to answer question 6, we need to find which answer choice McKay's team would agree with.

McKay's team thinks that this particular meteorite contains evidence of life on Mars. In the second paragraph, the author presents some points from people who are skeptical of this claim, and then shows how McKay would respond to these points:

Skeptical point #1: Maybe the meteorite just got contaminated by PAHs from earth.
- McKay response: There are more PAH's deeper in the rock than on the surface
Skeptical point #2: PAHs can be produced by non-organic processes
- McKay's response: the particular combination of PAHs in ALH84001 is more similar to the combinations produced by decaying organisms than to those originating from non biological processes.

Question #6 asks particularly about the PAHs mentioned in skeptical point #2. What would McKay's team think about these non-organic PAHs?

Quote:

(B) These PAHs are not likely to be found in any meteorite that originated from Mars.

There's no evidence that McKay's team would agree with this. McKay says that the particular combination of PAHs in this specific meteorite seem organic in origin. He never argues that non-organic PAHs wouldn't be found in ANY rocks coming from Mars.

Sure, McKay is trying to convince the skeptics that the meteorite contains evidence of life on Mars. But there's no indication in the passage that McKay would bury his head in the sand and deny that non-organic PAHs exist on Mars. Instead, he takes the much more reasonable stance that the particular PAHs in this particular meteorite are more likely to be organic in nature.

There's no evidence that McKay's team would agree with (B), so eliminate this answer choice.

A note on extreme language: it is definitely important to notice extreme language in an answer choice -- here, the word "any" makes (B) a very strong statement. However, the mere presence of extreme language isn't enough to make a decision (there are plenty of correct answers that contain strong language). Instead, just think about how those key words impact the meaning of the answer choice as a whole, and then use this assessment when considering whether you can eliminate that answer choice.

Quote:

(D) These PAHs are likely to be found in combinations that distinguish them from the PAHs produced by organic processes.

Does this merely regurgitate info from the passage? Yeah, kind of (although not explicitly). Is that a deal breaker? Not at all! We're just trying to find a statement that McKay would agree with, and he would definitely agree with (D). McKay argues that the combination of PAHs in the meteorite indicates that they originated from an organic source. So, he would agree that non-organic PAHs are likely to be found in combinations that can be distinguished from organic PAHs.

McKay's team would agree with (D), so (D) is the correct answer to question 6.

I hope that helps!

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GMATNinja

I was just watching your YouTube video discussing Question 5 and wanted to ask for some clarification on why Option D — "It suggests how the terrestrial contamination of ALH84001 might have taken place." — is incorrect.

My reasoning was that this seemed like a valid choice, since the second paragraph explores skepticism around the meteorite and introduces the possibility of terrestrial contamination.

Am I mistaken in applying the meaning of a sentence across subsequent paragraphs, or should I be interpreting each sentence strictly within the context of its own paragraph and those that precede it? For example, should the sentence "When microbes die, their organic material often decays into PAHs." be understood only in the context of the preceding discussion, without referencing content in the following paragraph?

Thanks in advance for your help!

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Updated on: 30 Jun 2025, 08:33

Originally posted by GMATNinja on 30 Jun 2025, 08:33.
Last edited by GMATNinja on 30 Jun 2025, 08:33, edited 1 time in total.

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Question 5

canadianmonkey3

url=[https://gmatclub.com:443/forum/memberlist.php?mode=viewprofile&un=GMATNinja]GMATNinja[/url]

I was just watching your YouTube video discussing Question 5 and wanted to ask for some clarification on why Option D — "It suggests how the terrestrial contamination of ALH84001 might have taken place." — is incorrect.

My reasoning was that this seemed like a valid choice, since the second paragraph explores skepticism around the meteorite and introduces the possibility of terrestrial contamination.

Am I mistaken in applying the meaning of a sentence across subsequent paragraphs, or should I be interpreting each sentence strictly within the context of its own paragraph and those that precede it? For example, should the sentence "When microbes die, their organic material often decays into PAHs." be understood only in the context of the preceding discussion, without referencing content in the following paragraph?

Thanks in advance for your help!

There is certainly no "rule" stating that you MUST limit yourself to the paragraph in which the sentence is found, when examining the function of a sentence.

But in this case, the last sentence of the first paragraph is not there to explain HOW the terrestrial contamination might have taken place. In fact, there's nothing in the passage explaining or suggesting how the terrestrial contamination might have occurred. We're told that terrestrial contamination may have happened, but we are not told how, exactly, that terrestrial contamination might have happened.

Everyone agrees that the meteorite contains PAHs. The last sentence of the first paragraph gives a reason to believe that the PAHs MIGHT have come from microbes (tiny living organisms). In other words, microbes might be the source of the PAHs found in the meteorite. This fits with choice (A).

More broadly, the sentence in question is evidence -- not proof -- that McKay's theory might be correct. That's why this sentence appears in the first paragraph and not the second. Yes, there is skepticism, but the sentence in question is not there to explain or support that skepticism.

I hope that helps!

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