Sentence Correction - Verbal and Reasoning

Directions to SolveWhich of phrases given below each sentence should replace the phrase printed inboldtype to make the grammatically correct? If the sentence is correct as it is, mark 'E' as the answer.
Q1:

What does agonise me most is not this criticism, but the trivial reason behind it.

A most agonising me

B agonises me most

C agonising me most

D I most agonised

E No correction required

ANS:B - agonises me most

No answer description is available.