You are driving a heavy vehicle and dense fog reduces visibility significantly. What is the correct response?

1. Maintain your normal speed and follow the vehicle ahead closely to see the road
2. Reduce speed significantly, use low-beam headlights (and fog lights if fitted), and increase following distance
3. Turn off your headlights so oncoming drivers are not dazzled
4. Stop in the traffic lane with hazard lights on and wait there indefinitely