What is the appropriate action when driving in fog?

Answer: C — Use low beam headlights

When driving in fog, using low beam headlights is the appropriate action because they illuminate the road immediately in front of the vehicle without causing excessive reflection off the fog. High beam headlights can create a blinding effect, as the light reflects back off the foggy moisture in the air, reducing visibility instead of enhancing it. Driving at the speed of traffic may not be safe in foggy conditions, as reduced visibility typically requires slower speeds to maintain control of the vehicle and respond to hazards. Turning off the headlights entirely is also unsafe, as it limits visibility for both the driver and other road users. Therefore, using low beam headlights is essential for clear visibility and ensuring safety while navigating through fog.