When a driver spots a visually impaired pedestrian using a white cane or a guide dog preparing to cross the roadway, what is the mandatory protocol?

1. Sound the horn repeatedly to indicate that the car has the right-of-way
2. Decelerate, stop, and proactively yield the right-of-way to allow them to cross safely
3. Drive around the pedestrian at normal traveling speed
4. Flash headlights rapidly to signal the guide dog to hurry