The answer would be "Prolific" as that meant he produced a great deal of work.
I would say that the correct sentence is (D).
answer (C) has the apostrophe in the wrong place, and in (B) the comma doesn't really break up the sentence properly. 'the shaggy brown,' doesn't make sense on its own. and in (A), there isn't any commas at all
Where is passage? You didn’t show it
