What are you required to do according to the following road sign?

1. Honk continuously to warn the tractor drivers.
2. Give right-of-way to an agricultural vehicle on a freeway.
3. Turn-on the lights and stay on the right of the road.
4. Correct answer: Slow down as you may encounter a heavy and slow agricultural vehicle.

WhySlow down and be ready to meet a slow work vehicle or tractor. Rules about headlights or motorway priority have nothing to do with it.