C is the answer ..
If a person studies four hours a day for the GMAT, he will score in the top 10 percent. Every student at Harvard School of Law scored in the top 10 percent. Thus, Sarah who is studying at Harvard School of Law must have studied at least four hours a day.
The reasoning in the argument above is flawed because it
If a person studies four hours a day for the GMAT, he will score in the top 10 percent.
But reverse may not be true i..e a student in top 10 percent score may not necessarily have studied 4 hrs a day
(A) fails to consider that many students at Harvard studied more than four hours a day.
(B) fails to consider that studies have shown that studying one subject more than three hours a day can be counterproductive.
(C)
fails to consider that studying less than four hours a day may be sufficient for some people to score in the top 10 percent.
(D) fails to consider that people who studied less than three hours a day did not get into Harvard.
(E) fails to consider that an additional eight hours a week of studying is an impossible burden for most college students.