Hi Samrat,
This is a very common form of argument on the GMAT. The evidence establishes a correlation between A and B, then relies on that to conclude that one causes another. A correlation will show up in two wayson the GMAT: either A precedes B (or B precedes A) or A and B occur simultaneously. The necessary assumption here is that there are no other causes.
There are a few different ways to weaken this argument although they all share on thing in common: they all attack this necessary assumption.
Here the author establishes a correlation between high protein ingestion and increased likelihood of suffering from insomnia, and then relies on that to conclude that high protein causes insomnia.
The correct answer points to a third factor (other characteristics) that is correlated with both high protein ingestion and increased likelihood of suffering from insomnia. This opens up the possibility that it is not high protein causing insomnia but rather the third factor that is causing both high protein and insomnia.
Kaplan Teacher in Toronto
