Scarlett should clean Room 608 first because it is a check-out room. This means that the guests have already left and the room needs to be cleaned and prepared for new guests. The other rooms listed are either stayover rooms, which means the guests are staying for another night and the room can be cleaned later, or out-of-order, which means the room is not currently in use and does not need immediate attention. Room 607 is due out, but it is still occupied, so it can be cleaned after the guests check out.