Let's look at why A strengthen the conclusion. A says that Smithtown University (SU)'s fund-raisers were no more successful than other fundraisers in their contact with new donors.
A doesn't mean that. A的意思是S大学联系从未捐款的人跟其它大学同样频繁
C 能support the conclusion. 大部分捐款来自以前的捐款人, 而且大学没联系他们. 大学联系了其他潜在捐款人, 使用说明80%捐款了. 所有这些说明没新的捐款人