When driving a passenger coach along narrow mountain roads with blind curves and steep grades, what is the golden safety rule (山路驾驶安全原则)?

1. Drive in the center of the road at high speed to maintain momentum
2. Overtake slower vehicles inside blind mountain curves
3. Coast downhill in neutral to keep engine temperatures low
4. Slow down, sound the horn, and keep to the right side (减速、鸣笛、靠右行), and yield to ascending vehicles when meeting on narrow grades