What is the best speed to drive in heavy fog conditions?

Answer: A — 30mph or below

In heavy fog conditions, it is crucial to drive at a reduced speed to ensure safety on the road. Driving at a speed of 30mph or below is recommended as it allows for better visibility and gives the driver more time to react to any obstacles or sudden changes in the road conditions that may be obscured by the fog. Driving at higher speeds increases the risk of accidents as visibility is significantly reduced. Therefore, driving at 30mph or below is the best option in heavy fog conditions to prioritize safety for yourself and other road users.