You are riding a bicycle along the right edge of the road, and a city bus ahead has stopped at a bus stop to let passengers off. What is the correct way to proceed?

1. ①A bicycle may never pass a vehicle on its right, so always pass the bus on its left
2. ②Pass on the right of the bus, sounding the bell and speeding up so passengers get out of the way
3. ③When the bus is stopped, ride up onto the sidewalk and go between pedestrians
4. ④You may pass on the right of the bus, but slow down or stop if necessary, paying attention to the safety of alighting passengers