While microscopes sometimes used to distinguish poisonous mushroom species apart from their innocuous counterparts, identification by sight remains a more common method.
(A) While microscopes sometimes used to distinguish poisonous mushroom species apart
(B) While microscopes are sometimes used to distinguish poisonous mushroom species apart
(C) Although the use of microscopes to distinguish poisonous mushroom species
(D) Although microscopes, which are sometimes used to distinguish poisonous mushroom species apart
(E) Although microscopes are sometimes used to distinguish poisonous mushroom species
Scroll down for the answer.
Answer: E
Passive Voice Required, Idiom
Although passive constructions are frequently incorrect on the GMAT, in this case one is required for the sake of meaning. Microscopes themselves do not use anything; rather, they are used. That eliminates (A). (C) is incorrect because a clause begun by although must contain a main verb, and here there is only a noun (the use). (D) is incorrect because it creates a non-essential clause that cannot be crossed out of the sentence without creating nonsense: Although microscopes…identification by sight remains a more common method. (B) and (E) are very similar, but there is one key difference: the idiom is “distinguish x from y” – the word apart is unnecessary. That eliminates (B) and makes (E) the answer. Note that the question of while vs. although is only a distraction here.
