GWD6-Q2 C到底错在哪里了呢

GWD6-Q2:

According to its proponents, a proposed new style of aircraft could, by skimming along the top of the atmosphere, fly between most points on Earth in under two hours.

A.     According to its proponents, a proposed new style of aircraft could, by skimming along the top of the atmosphere, fly between most points on Earth in under two hours.

B.      By skimming along the top of the atmosphere, proponents of a proposed new style of aircraft say it could fly between most points on Earth in under two hours.

C.     A proposed new style of aircraft could fly between most points on Earth in under two hours, according to its proponents, with it skimming along the top of the atmosphere.

D.     A proposed new style of aircraft, say its proponents, could fly between most points on Earth in under two hours because of its skimming along the top of the atmosphere.

E.      According to its proponents, skimming along the top of the atmosphere makes it possible that a proposed new style of aircraft could fly between most points on Earth in under two hours.

正解为A,我不明白C错在哪里了。看了CD的帖子，解释有如下：

1）with 不如用by好。可是with在句尾也作为方式状语啊，by不就是方式状语吗？难道是因为according to做插入语不能不如在句首更明确的修饰主句？

2）it应该用its。是不是在with
                    it
                skimming along the top of the atmosphere中，it为代词，skimming为分词， along the top of the atmosphere为介词短语，不符合独立主格的形式，应该是with+n./pron.+ 分词/介词短语? 如果改成with
                    its
                skimming along the top of the atmosphere,是不是就满足了独立主格的形式啦。its
                skimming 动名词做名词成分，along the top of the atmosp为介词短语。

望NN或斑竹能解释一下

明细啦，谢谢斑竹