NN们过来看！GWD-TN-8 29题，谁能解释！

gmatbiguo

Smithtown University’s fund-raisers succeeded in getting donations from 80 percent of the potential donors they contacted.  This success rate, exceptionally high for university fund-raisers, does not indicate that they were doing a good job.  On the contrary, since the people most likely to donate are those who have donated in the past, good fund-raisers constantly try less-likely prospects in an effort to expand the donor base.  The high success rate shows insufficient canvassing effort.
Which of the following, if true, provides more support for the argument?
A.    Smithtown University’s fund-raisers were successful in their contacts with potential donors who had never given before about as frequently as were fund-raisers for other universities in their contacts with such people.
B.    This year the average size of the donations to Smithtown University from new donors when the university’s fund-raisers had contacted was larger than the average size of donations from donors who had given to the university before.
C.    This year most of the donations that came to Smithtown University from people who had previously donated to it were made without the university’s fund-raisers having made any contact with the donors.
D.    The majority of the donations that fund-raisers succeeded in getting for Smithtown University this year were from donors who had never given to the university before.
E.    More than half of the money raised by Smithtown University’s fund-raisers came from donors who had never previously donated to the university.
答案选A，但是我觉得选C。题目不是要我们加强This success rate, exceptionally high for university fund-raisers, does not indicate that they were doing a good job. A我觉得是在削弱啊。NN们怎么理解的？

sdcar2010

C is out of scope because the stimulus focuses on the successful rate of 80% among the potential donors the fund-raisers CONTACTED.  Who cares about those the fund-raisers did not contact?  It has no impact on the argument.

On the other hand, A is a strengthener. In the stimulus, the premise says that “the people most likely to donate are those who have donated in the past.”  The author is building a case against the 80% successful rate as a bench mark for a job well-done.  Rather, the author accuses the fund-raisers with a not-so-good canvassing effort based on the 80% success rate, implying that they did not find NEW donors more efficiently than fund-raisers in other universities.  If A is true, then they were only as “successful in their contacts with potential donors who had never given before” as other universities. Thus, they must have concentrated on the people that have donated before in order to get the 80% success rate.