What beam should you use while driving in thick fog to reduce glare?

Answer: B — Low beam

Using low beam headlights while driving in thick fog is the best choice because they provide adequate illumination without causing significant glare. In foggy conditions, high beam headlights can reflect off the fog droplets in the air, creating a blinding effect that reduces visibility rather than improving it. This is due to the way light is scattered in fog; high beams send light upward and outwards, which can create a wall of light that obstructs the driver's ability to see clearly. Low beams, on the other hand, are designed to project light closer to the road and into a wider area directly in front of the vehicle, allowing better visibility without causing excessive reflection. Utilizing low beam headlights helps drivers maintain better sightlines and reduces the potential for accidents caused by reduced visibility in foggy conditions.