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


SOurce OG 12
OA is A

Query

OG 12 says, So X as to Y not correct idiom ! huh ?!?

MGMAT says So X as to Y is correct


What am I missing here ?