A. - Does it take you long to do your homework?
B. - Oh, very long.
Essentially, this is the preferred choice. However, note that there is a slight shift in meaning between
1. - Does it take you long to do your homework?
Here, the emphasis is on how quick or slow he is in doing the homework. This could be owing to the fact that there is a lot of homework to do, or he's not bright!
2. - Does it take very long to do your homework?
Here, the emphasis shifts to how much homework is being given, and hence, correspondingly, how much time it takes to complete.
Homework does take time, so we usually say, 'does it take very long', giving it the meaning, 'does it take so much time that it feels like a burden?"
the choice of answers:
In the negative : Not long
In the affirmative : 1. A long time. B Too long.