Multiple choice

[trencyfu]

Twenty minutes have passed; the bus ______ come at any moment. A. shall B. should C. can D. must
Which should I choose?
Thanks!

[riquecohen]

Which do you think you should choose?

[BobSmith]

[not a teacher]

Although "shall" is less common in AmE, I can think of cases where I would use any of those choices.

[5jj]

[not a teacher]Although "shall" is less common in AmE, I can think of cases where I would use any of those choices.

Well, Cinderella's fairy godmother can promise 'You shall go to the ball', but I cannot imagine anybody naturally saying 'the bus shall come at any moment'.

[shannico]

Well, Cinderella's fairy godmother can promise 'You shall go to the ball', but I cannot imagine anybody naturally saying 'the bus shall come at any moment'.

I agree.To me it sounds like an assumption.
I can't think of a suitable example with caneither though, whereas could would fit in.

[bhaisahab]

The expected answer is probably "should". It's a bad test question as there are other possible answers.