请教gwd-2-14

Q14:

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?

1. 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.
   



2. 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.
   



3. 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.
   



4. 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.
   



5. More than half of the money raised by Smithtown University’s fund-raisers came from donors who had never previously donated to the university.

这题我选了c，手上有两种答案a、c，请nn帮助确认一下解释一下。谢谢。

我下载的携隐mm说此题选A，因为

未捐赠人的比率和别的大学一样高，说明80%的高成功率不是来自未捐赠人。

本来我是选C的，看到这句话以后迷惑了....

there are many wonderful explanations in the following link. my explanation is offered in 26th level

http://forum.chasedream.com/dispbbs.asp?BoardID=24&ID=57558

看到了，选A。非常感谢