When is it proper to use low beam headlights?

Answer: B — During the day on narrow country roads

Using low beam headlights on narrow country roads during the day is appropriate because it enhances visibility and helps you be seen by other drivers, particularly in potentially hazardous situations. Narrow roads often have limited visibility due to trees, curves, or other obstructions, and using low beams can improve safety by allowing you to see and be seen more clearly. While low beam headlights are also necessary during various weather conditions, including rain, fog, or at night, the focus here is on the specific scenario of narrow country roads during daylight. Such roads may not be well lit, and daylight does not guarantee that visibility is sufficient without the additional illumination from low beams.