What must you do when driving in foggy conditions?

Answer: C — Reduce your speed and use low beams

When driving in foggy conditions, it is essential to reduce your speed and use low beams. Fog can significantly decrease visibility, and using low beams helps illuminate the road immediately in front of you without causing glare that can reflect off the fog. High beams can actually worsen visibility in fog, as the light gets scattered by the moisture in the air, creating a "whiteout" effect that makes it even harder to see. Additionally, reducing your speed is crucial because it allows you more time to react to any obstacles or changes in the driving environment. Maintaining a slower speed enhances safety for yourself and others on the road, as stopping distances are longer in poor visibility conditions. By doing this, you maintain better control over your vehicle and improve your chances of avoiding accidents.