When driving in fog, how should you adjust your speed?

Reducing speed and increasing following distance is the appropriate approach when driving in fog due to the significantly reduced visibility that fog can create. Lowering your speed allows for better control of the vehicle and more time to react to any sudden obstacles or changes in traffic conditions. Increasing your following distance provides additional space to react to the vehicle ahead of you, which is crucial when visibility is poor.

Other options suggest either increasing speed or maintaining usual speed, which can lead to dangerous situations, as visibility is compromised and stopping distances are increased. Driving consistently slow might be too vague; however, maintaining a slow speed without adjusting for safety margins can also be risky. It's important to strike a balance between being cautious and ensuring that you can still operate your vehicle in a manner that is safe and effective under the circumstances.