In Texas, drivers must use their headlights:

1. When they are tired.
2. When their vehicle has a mechanical problem.
3. 30 minutes after sunset until 30 minutes before sunrise. ✓
4. During the day in clear weather.

Answer: C. 30 minutes after sunset until 30 minutes before sunrise.

Drivers in Texas must use headlights from 30 minutes after sunset until 30 minutes before sunrise.

Why this is the answer

The Texas handbook ties the headlight requirement to a specific window: it starts half an hour after sunset and ends half an hour before sunrise. It also requires headlights whenever people or vehicles cannot be seen clearly at 1,000 feet. That makes the sunset-to-sunrise window the correct choice. The other listed situations are not the handbook's trigger for headlights.

Why the other answers are wrong

• A. When they are tired. — Feeling tired is not a headlight rule in the handbook; the requirement is tied to light and visibility, not fatigue.
• B. When their vehicle has a mechanical problem. — A mechanical problem is not listed as a reason to turn on headlights; the passage gives time-of-day and visibility conditions.
• D. During the day in clear weather. — Clear daytime driving is outside the required window, so headlights are not required by this rule then.

Remember it

Think of it as sunset plus 30 minutes to sunrise minus 30 minutes.