请教两道语法题

longtaolongtaoUID: 2155019

Archaeologists are generally in agreement about the reasons for the astonishing wealth------within the Hopewellian graves located in what is now the state of Ohio.
A.        that contained
B.        were containing
C.        that no contain
D.        contained
答案选D,可我觉得这为什么不用containing,如果D可以,A错在哪?

The differences of many ice creams are the result of the quality, richness, and freshness of the ingredients.
ETS的标准答案是开头的of many错误,为什么,如何改?

airhoverUID: 2106738

因为答案没有containing..

of-> between

longtaolongtaoUID: 2155019

differences后面是可以接of,我查过字典了