Always, Always, Always with the Title Block showing the lower right-hand corner up. I was always taught to show the sheet number (which has always been in the lower right... anyone who does otherwise is looking for a fight) at least, if not the whole title block, when folding drawings.
We never work with C... always B and D.
Looking at the numbers, you should fold it in a manner that gives you a 9x12 piece... So I guess fold it in half twice, once each way, so that the number is showing. I can't say for sure though.