Which one do you want to send?
A very good question. With so many units deployed throughout the world, we are becomingly very thin. The recent news that the SecDef is positioning to make Guard and Reserve units active duty should tell you how thin we are. I've even heard rumors of calling back retired personnel and moving IRR soldiers into units. (Considering the SecDef's decision to nominate Gen. Schoonmaker as Army CoS, this is not out of the realm of possibilities).
Personally, I'd probably rotate 10th Mountain to the region, but their OPTEMPO is insane right now.