When two vehicles meet on a narrow steep mountain slope, what is the statutory right-of-way rule between the uphill vehicle and the downhill vehicle?

1. The downhill vehicle always has absolute priority
2. The uphill vehicle has priority (上坡车先行); however, if the downhill vehicle is already halfway down the slope and the uphill vehicle has not begun climbing, the downhill vehicle goes first
3. Whichever vehicle flashes high beams first goes first
4. The downhill vehicle should accelerate down to clear the hill quickly