When driving in fog, you should:

1. Use your high beam headlights.
2. Use your parking lights.
3. Use your low beam headlights. ✓

Answer: C. Use your low beam headlights.

When driving in fog, use your low beam headlights.

Why this is the answer

The handbook's safe driving section says that if you must drive in heavy fog or smoke, you should drive slowly and use your low-beam headlights. It explains that high beams reflect back off the fog and cause glare, so they make it harder to see. The other section adds that when fog or other conditions keep you from seeing other vehicles, your headlights should be on, and that if you need wipers because of fog, rain, or snow, low beams are required.

Why the other answers are wrong

• A. Use your high beam headlights. — High beams bounce off fog and create glare in your own eyes, which is why the handbook tells you to use low beams instead.
• B. Use your parking lights. — The handbook says it is illegal to drive using only parking lights, and it specifically warns against driving in fog with only parking or fog lights.

Remember it

Think of fog as a wall that throws light back at you: keep the beam low so it stays on the road, not in your eyes.