Which action must a driver take when approaching a railroad crossing?

Answer: B — Slow down and look both ways

When approaching a railroad crossing, a driver must slow down and look both ways as a safety measure. This action is critical because train schedules can be unpredictable, and a train can approach the crossing at high speeds without warning. By slowing down, the driver has enough time to assess the situation, check for any approaching trains, and ensure it is safe to cross. Looking both ways allows the driver to identify any trains that may be coming from either direction and increases their awareness of potential hazards. This practice is essential, as trains can be difficult to see and hear, especially in the presence of noises from traffic or other environmental factors. While stopping for all crossings or passing without stopping if clear may seem like reasonable options in some contexts, they do not prioritize the necessary precautions of ensuring safety before crossing the tracks.