If fog suddenly descends and visibility declines rapidly, you should...?

Answer: B — Pull off the road and wait for conditions to improve

When fog occurs and visibility becomes severely limited, pulling off the road and waiting for conditions to improve is the safest course of action. This approach minimizes the risks associated with driving in low visibility, where it is difficult to see other vehicles, pedestrians, or road signs, increasing the likelihood of accidents. By pulling over, you also avoid the dangers of disorientation or panic that may arise from navigating through thick fog. Waiting for conditions to improve ensures that you are in a safe position where you can reassess the situation without the added risk of being on the road. It's essential to make this decision when visibility drops suddenly, as it allows you to avoid excessive speed, which could lead to losing control of the vehicle or colliding with other road users who may also be struggling with limited visibility.