What is the rule regarding headlights during inclement weather?

Using headlights when windshield wipers are in use is important because it significantly enhances visibility during inclement weather such as rain, fog, or snow. This rule ensures that not only does the driver have a better view of the road and surrounding environment, but it also makes the vehicle more visible to other drivers. When windshield wipers are activated, it indicates that conditions have worsened, making it essential to turn on headlights, even during daytime. Many drivers may not realize how quickly weather conditions can change the visibility on the road, and using headlights optimally can aid in preventing accidents.

The other options don't address the specific need prompted by using windshield wipers and thus do not provide the same level of safety in adverse weather conditions. For instance, using headlights only at night ignores the need for visibility during the day in poor weather, while relying on visibility reductions or heavy traffic does not encompass all situations where enhanced visibility is crucial, particularly when wipers are active.