请教OG12 37题

allygmat7

37. Although schistosomiasis is not often fatal, it is so
debilitating that it has become an economic drain on
many developing countries.
(A) it is so debilitating that it has become an
economic
(B) it is of such debilitation, it has become an
economical
(C) so debilitating is it as to become an economic
(D) such is its debilitation, it becomes an economical
(E) there is so much debilitation that it has become
an economical

请问各位C错在哪里？

Fadaways

请解释一下影响只带最佳结构的问题呢，我不太明白，谢了

allygmat7

谢谢

sunflower88

so ... as to... 不用倒装；它也影响了主从句对位指代（主句主语it指代从句主语schistosomiasis）的最佳结构。