pasty
A different kind of pasty
Assuming Rooney starts up front, either have done enough to earn a place IMO, but I would personally give it to Welbeck to start with, given the additional club-based teamwork between the two, then bring on the big man if we need him later.
This.
I think the fact Rooney and Wellbeck play together all the time gives Wellbeck the advantage, but as you say, have Carroll on the bench ready to get amongst it if we need to. Maybe even as someone else suggested, have all three of them on the pitch if we still need a goal with 10 mins left or so.