What must a conductor do when approaching a grade crossing?

Answer: B — Ensure the train is slowed, sound the horn, and check for oncoming traffic

When approaching a grade crossing, the conductor must ensure that the train is slowed, sound the horn, and check for oncoming traffic. This is critical for safety because grade crossings are points where trains intersect with roadways, and other vehicles may be present. By slowing the train, the conductor allows more time to assess the conditions at the crossing and react appropriately if any hazards are present. Sounding the horn serves as an audible warning to motorists and pedestrians who may not be aware of the train's approach, increasing their awareness and prompting them to ensure it is safe to cross. Checking for oncoming traffic is essential because it allows the conductor to determine if any vehicles or persons may obstruct the crossing or place themselves in danger. This approach prioritizes safety for everyone involved, ensuring that the train can proceed through the crossing without incident.