求助：SC93

Hattielin87UID??2777729

题目是这样的：
93.  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
答案是A，但是我选的是C。A不是很wordy吗，大全的解释是这样的：Choice A is best:  is  links the noun  schistosomiasis  with its modifier,  debilitating,  and  so debilitating that  idiomatically introduces a clause that provides a further explanation of  debilitating. Choices B, D, and E produce awkward, wordy, imprecise, or unidiomatic phrases by substituting the noun debilitation for the modifier debilitating. Choices B and D fail to introduce the explanatory clause with  that,  and C uses an awkward and wordy construction in place of a that...  clause. Finally, B, D, and E wrongly use  economical  instead of  economic to  mean
―pertaining to the economy.怎么都看不太明白，有没有大虾站出来点拨一下~~

Hattielin87UID??2777729

怎么没有人理，自己顶一下！