GWD-4-Q4

A new hair-growing drug is being sold for three times the price, per milligram, as the drug’s maker charges for another product with the same active ingredient.

A.      as

B.       than

C.      that

D.      of what

E.       at which

OA-C that 在这里做什么成分呢？我选了D， the price of 不对吗？

明白了~~~

追加一个问题,这里的 that是引导定语从句吗?若是,在从句中做宾语的that是不是可以省略呢?

搜吧，这些问题回答了N遍了。

或者上Manhattan Gmat上找。