一道CR，求答案

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.

GWD31给的答案是C, GWD24给的是A，到底答案是那个啊？