When driving in fog:
- Use your parking lights.
- Use your low beams. ✓
- Use your high beams.
- It makes no difference which lights you use.
Answer: B. Use your low beams.
In fog you should drive with your low beams on.
Why this is the answer
The handbook's low-visibility section says that in fog you must turn on your headlights, and it adds that parking lights do not count as a substitute. It also tells you to drive with lights on low beam, because high beams bounce off the fog and make it harder to see. That is why low beams are the right choice while high beams and parking lights are not.
Why the other answers are wrong
- A. Use your parking lights. — Parking lights are not a substitute for headlights in low visibility, so they are not what you should rely on in fog.
- C. Use your high beams. — High beams reflect off the fog and cut your visibility even further, so they make things worse.
- D. It makes no difference which lights you use. — The handbook treats beam choice as a real rule with a difference, because high beams reflect off fog while low beams are what you are told to use.
Remember it
Think of fog as a mirror: the brighter your beam, the more it bounces back at you, so keep it low.