I . . . . . . . . this book since morning.

A. had been reading

B. has been reading

C. have had read

D. shall be reading

Answer: Option A

Solution(By Examveda Team)

We use the past perfect continuous to talk about actions or events which started before a particular time in the past and were still in progress up to that time in the past.
Example: It was so difficult to get up last Monday for school. I had been working on my essays the night before and I was very tired.