Under Article 47 of the Road Traffic Safety Law, what is the mandatory requirement when a motorcycle approaches a pedestrian crosswalk (斑马线) where pedestrians are crossing?

1. Sound horn continuously and accelerate through the gaps
2. Flash headlights and weave around the pedestrians
3. Wave hands to tell pedestrians to stop and wait
4. Decelerate, and come to a complete stop to yield the right of way to pedestrians (减速慢行并在行人通行时停车让行)