ruplun wrote: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

I find the solution to be C ,BUT in OG10 its given as A..Please comment

Hello,

The problem with C is that there is no "as to..." main clause parallel to the "so..." clause. When the subject and verb both follow the "so" in the idiom "so... as to" you also need to have a subject and verb after "as to" or you will have branched off at different places:

SO it is debilitating
AS TO become

Better:

It is SO debilitating
..... AS TO have become

But you don't have this option. And in any case you can eliminate B, D and E since "economical" is uncalled for ("economic" means "relating to the economy or to the field of economics," whereas "economical" means "sparing or tending to use resources efficiently").

Hope this helps!