When approaching a pedestrian crossing where another vehicle in the adjacent lane has slowed down or stopped, what must you do?

1. Do not overtake; slow down and stop if necessary to allow pedestrians to cross safely
2. Accelerate quickly to clear the crossing before the pedestrian steps onto your lane
3. Sound your horn continuously to warn pedestrians and proceed past the stopped vehicle
4. Overtake the stopped vehicle on the right using the pedestrian sidewalk