(A) that such a study has not been practical
(B) that studying it that way has not been impractical
(C) for such studies as this to have been impractical
(D) as to not make such a study practical
(E) as to be impractical of study
Solution:
Idioms
In A, “so x that y” is idiomatic and hence, A is the best choice.
In B, the use of “not been impractical” is incorrect.
In C, “…such studies as this to have been impractical.” is awkward. “to have been” is wrong tense.
In D, “so small as to not…” is awkward. Furthermore, wrong tense has been used.
In E, “impractical of study” is incorrect.
Sentence Correction - 1000 Questions with Solution:
