Correct way to answer a question containing "must"

Question

What's the right way to answer a question in English, in which the "actors" must do something?

For example,

Who must choose their own club here?

If it's two people - Bob and Billy - who must choose clubs, how should the correct answer go then?

1. Bob and Bill do.

2. Bob and Bill must.

3. Bob and Bill.

or what?

Answer 1

No.1 isn't normal usage at all,

No.2 and No.3 are pretty much interchangeable.