When making an unprotected left turn at a signalized intersection (green ball signal), what right-of-way rule must be observed?

1. Oncoming straight-through vehicles must stop and yield to left-turning traffic
2. The left-turning driver has absolute priority over all other movements
3. Sound the horn and complete the turn before oncoming cars arrive
4. Yield to oncoming vehicles proceeding straight or turning right, and yield to crossing pedestrians