When driving in fog:

1. Use your parking lights.
2. Use your low beams. ✓
3. Use your high beams.
4. It makes no difference which lights you use.

Answer: B. Use your low beams.

Use your low beams when driving in fog.

Why this is the answer

The Texas handbook lists low beam headlights as the choice for driving in fog, heavy rain, sleet, snow, or dust. It gives this as a specific situation where low beams should be used, alongside following closely, approaching another vehicle, and driving on lighted roads. So when fog reduces what you can see, the handbook's listed choice is low beams, not another light setting.

Why the other answers are wrong

• A. Use your parking lights. — Parking lights are mentioned only for parking on an unlighted highway at night, not for driving in fog.
• C. Use your high beams. — The handbook names low beams for driving in fog, not high beams.
• D. It makes no difference which lights you use. — The handbook gives a specific headlight choice for fog, so it does matter which lights you use.

Remember it

Fog, rain, sleet, snow, dust: remember low beams are the listed choice.