Subscribe TechModgy to learn about new technologies!

In the following questions, a sentence has been divided into four parts and marked a, b, c and d. One of these parts contains a mistake in grammar Idiom or syntax. Identify that part and mark it as the answer.

A. He was reading

B. very hard for

C. the last six months

D. still he failed.

Please do not use chat terms. Example: avoid using "grt" instead of "great".