Under Article 48 of the Road Traffic Safety Law Implementation Regulations, when two vehicles meet on a narrow mountain slope where passing is difficult, which vehicle has the statutory right-of-way?

1. The vehicle traveling uphill has right-of-way; however, if the downhill vehicle is already halfway down the slope and the uphill vehicle has not begun climbing, the downhill vehicle goes first
2. The downhill vehicle always has absolute right-of-way regardless of position
3. The larger passenger bus must always force smaller vehicles into the ditch
4. Whichever vehicle flashes its high beams first has statutory right-of-way