Question

15. he is busy --- his work
(A) of (B) at (C) with [D] about​

Answer 1

He is busy with his work .

With is a preposition which tells the place where the noun is . They tell the position of the noun and thus called preposition .

Examples :

1. She came by bus .
2. She sat on the stool .
3. Hey ! Can you come down ?

And here accordingly we have taken Busy with his work as a work being done is normally a work doing something and being busy with it .

So we be busy with a work .

Why not other options ?

• He is busy of his work is something that doesn't make any sense regarding the subject verb agreement .

• He is busy at his work is good with the place ; like adverb of Place but here with will suit the most .

• He is busy about his work is against grammatical rules.