question_answer

Below given is a sentence divided into four parts. One of the parts contains a grammatical error. Find the part and mark it as your answer.

Unless he does not return (I) / all the library books (II)/he will not be (III) /relieved from the service (IV).

A)  I                                 

B)  II

C)  III                               

D)  IV

E)  None of these