[求助]prep6选什么（网上未搜到）

6.  In the past several years, astronomers have detected more than 80 massive planets, most of them as large or larger than Jupiter, which circle other stars.

A. most of them as large or larger than Jupiter, which circle

B. most of them as large or larger than Jupiter and circling

C. most of them at least as large as Jupiter, circling

D. mostly at least as large as Jupiter, which circle

E. mostly as large or larger than Jupiter, circling

此题notes上没有答案。我选C，不知对吗？

另外most of 和mostly的区别是什么？请指教。

版主mm，非常感谢！