What should drivers be cautious about when they see a sign indicating "without pavement - road surface unknown"?

Answer: B — To slow down and check vehicle control

When encountering a sign that indicates "without pavement - road surface unknown," it is crucial for drivers to slow down and check vehicle control. This warning signals that the road conditions may be unpredictable, and the surface could be loose, uneven, or even unpaved. By reducing speed, drivers can better maintain control of their vehicle, which is essential for navigating potentially hazardous terrain. Slower speeds also give drivers more time to react to any sudden changes in road conditions or obstacles that may not be immediately visible. This cautious approach helps in ensuring both the driver’s safety and that of other road users.