The lights on your vehicle must be turned on anytime day or night when people and vehicles cannot be seen clearly for:

Answer: B — 1000 feet

The correct answer highlights the importance of safety and visibility on the road. In Texas, it is mandated that drivers must turn on their vehicle's lights anytime visibility is reduced to 1,000 feet or less. This requirement is particularly crucial in conditions such as fog, rain, or dusk, when visibility can be significantly impaired. Proper lighting ensures that drivers can see the road and any obstacles, while also making their vehicle more visible to others, reducing the likelihood of accidents. The other distances, while relevant for specific situations or guidelines, do not align with general visibility requirements set by traffic laws, making them less applicable in this context. Understanding the significance of maintaining visibility on the road reinforces the necessity of using vehicle lights appropriately under various circumstances.