Question

Billy _______ in the library this morning*
Ais study
Bis studying
Cstudy
Dare study

Answer 1

Billy is study dare in the library morning.

Answer 2

We need to fill the correct tense form here.

It is a simple question.

Billy is singular.

Now if we want to make a present continuous tense with study, it would obviously be is studying.

So the answer is B.

All the other options are not correct.

Grammar is the essence of any language, and English is no exception.