Hi mukherjee.tanu3,

This CR prompt is based on the concept of 'representativeness' - the idea that one small sample represents a larger group.

Here, we're told that Fullerenes were created in a lab under specific conditions (temperature and pressure). The prompt argues that the Fullerenes found in nature (in the Earth's crust) are essentially comparable to the ones created in the lab, so scientists can make deductions about the Earth's crust at the time those Fullerenes were formed.

We're asked to WEAKEN this logic, so we need an answer that essentially says that the Fullerenes made in the lab are NOT comparable to the ones found in nature...

Answer B talks about Fullerenes that hit a spacecraft, which is not relevant to the prompt. Answer D addresses the issue by pointing out that the Fullerenes in the lab do not match the ones found in nature.

GMAT assassins aren't born, they're made,
Rich

Hi mukherjee.tanuj3,

There's an important detail in the first sentence that most people would miss: fullerenes were FIRST found in the lab. The prompt argues that the lab discovery should give scientists a test case to evaluate fullerenes that appear in nature. The only way this argument is valid is if the fullerenes in the lab are comparable to the fullerenes found in nature (in basic terms: the fullerenes are the same). The prompt asks us to WEAKEN the argument; the easiest way to do so is to find an answer that gives us a reason for why the fullerenes are NOT the same.

Answer D tells us that the fullerenes found in nature are arranged in a previously UNKNOWN crystalline structure. This means that the fullerenes that were found in the lab were NOT in that crystalline structure (otherwise, the structure would have been known). By extension, this means that the fullerenes in the lab are NOT the same as the ones found in nature.

GMAT assassins aren't born, they're made,
Rich