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:

The crops are dying; it must not had rained.

A must had not

B must not be

C must not have

D must not have been

E No correction required

ANS:C - must not have

No answer description is available.