I believe this is the problem you're asking about:
Although fullerenes - spherical molecules made entirely of carbon - were first found in the laboratory, they have since been found in nature, formed in fissures of the rare mineral shungite. Since laboratory synthesis of fullerenes requires distinctive conditions of temperature and pressure, this discovery should give geologists a test case for evaluating hypotheses about the state of the Earth's crust at the time these naturally occurring fullerenes were formed.
Which of the following, if true, most seriously undermine the argument?
a) Confirming that the shungite genuinely contained fullerenes took careful experimentation
b) Some fullerenes have also been found on the remains of a small meteorite that collided with a spacecraft
c) The mineral shungnite itself contains large amount of carbon, from which fullerenes apparently formed
d) The naturally occurring fullerenes are arranged in a previously unknown crystalline structure
e) Shungite itself is only formed under distinctive conditions
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This is a Weaken question. Remember, if you find yourself stuck between two answer choices that both seem to have a deleterious effect on the conclusion, ask yourself: which one weakens the conclusion the most? There must be a recognizable, sizable difference between the correct answer and the second-best answer otherwise it wouldn't be a fair GMAT Critical Reasoning question.
NOTES:
Evidence: "F" 1st found in lab, later found in "S"; "F" in lab requires temp/pressure
Conclusion: Finding is basis for evaluating crust
Notice how important it is to (1) interpret the information provided in our own words, and (2) WRITE IT DOWN.
WHAT WOULD WEAKEN?
Before you can read the answer choices, write down your own pre-phrased answer. Since the argument is flawed, you might be able to think of 1-2 ways it can be weakened. Try to hone in on the BIGGEST flaw you can spot. What doesn't make logical sense?
The biggest jump here is between the temp/pressure of lab "F" and the earth's crust. This claim doesn't seem justified. There must be an assumption that the temp/pressure of "F" in the crust would be similar to the lab.
TO WEAKEN: Show lab cannot = earth's crust
(D) shows that the "natural" "F" is TOTALLY brand-new, and has NO CORRELATION to the lab "F". It must be correct.
(B) is utterly irrelevant. The passage's focus is in drawing a relationship between "F" in a lab and "F" in nature/earth's crust. (B) is in outer space and doesn't relate to the SCOPE of the argument.
