Official Solution:
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
Premise: Laboratory synthesis of fullerenes requires distinctive conditions of temperature and pressure.
Conclusion: The conditions of the Earth's crust at the time when these naturally occurring fullerenes were formed can be determined. (The conditions would be similar to the distinctive conditions of temperature and pressure under which laboratory fullerenes were synthesized.)
One underlying assumption could be that natural fullerenes, like laboratory fullerenes, also require similar conditions of temperature and pressure. If these conditions were different then the conditions of the Earth's crust at the time when these naturally occurring fullerenes were formed can not be determined from the laboratory conditions.
The reasoning above is based on the assumption about the similarity of the Natural fullerenes with Laboratory synthesis. The correct option would point out a dissimilarity that might have been caused by different conditions during the formation of natural fullerenes and laboratory fullerenes.
A. This option is irrelevant. It does not attack the argument (i.e. any assumption) in the passage. Hope much effort was taken to confirm the presence of fullerenes has no bearing on the argument.
B. This option is also irrelevant. Whether fullerenes are present outside the earth has no effect on the argument because finding fullerenes in a meteorite does not mean the fullerenes cannot have formed in the earth’s crust. It is very well possible that the meteorite and the earth’s crust had similar conditions, making it possible for fullerenes to form in both.
C. This option provides more evidence to the argument and thus is strengthening the argument.
D. CORRECT. First laboratory fullerenes (lab F) was synthesized - therefore the structure of lab F was already known before the discovery of natural fullerenes. Thereafter natural fullerenes (nat F) was discovered. Option D states that the crystalline structure of nat F is not previously known. This implies that the structure of nat F MUST be different from lab F. Hence the conditions at which both were created were not same. Hence laboratory conditions and earth conditions were not the same. Hence laboratory synthesis of lab F cannot help in finding out the condition of earth's crust during formation of natural F.
E. This option is itself the premise of the argument and hence cannot be weakening the argument.
Answer: D
_________________