What is the recommended action if fog is dense while driving?

Answer: C — Reduce speed and use low beams

When driving in dense fog, the recommended action is to reduce speed and use low beams. Reducing speed is essential because fog greatly reduces visibility, making it difficult to see other vehicles, traffic signals, and road signs. By slowing down, drivers can give themselves more time to react to unexpected obstacles or changes in traffic conditions, thus enhancing safety. Using low-beam headlights is crucial because high beams can reflect off the fog, causing glare and actually reducing visibility further. Low beams, on the other hand, provide adequate illumination of the road directly in front of the vehicle without creating that glare effect. While pulling over until visibility improves could be a safe option, it is important to proceed with caution when doing so to avoid creating a hazard on the road. Turning off the headlights or using high beams would be inappropriate reactions leading to reduced visibility and increased risk of accidents. Therefore, reducing speed while using low beams is the best practice in dense fog situations.