What must drivers do if they hear a train approaching at a railroad crossing?

Answer: B — Stop and wait for the train to pass

When drivers hear a train approaching at a railroad crossing, the appropriate action is to stop and wait for the train to pass. This response is crucial for ensuring safety at these potentially dangerous intersections. Trains cannot stop quickly, and their speed can be deceiving; therefore, stopping allows drivers to gauge the train's distance and speed accurately. By waiting for the train to pass, drivers minimize the risk of an accident, as trains have the right of way over all other vehicles and pedestrians at crossings. Additionally, there are often warning signals, such as lights and bells, that indicate an oncoming train, reinforcing the need to halt. This practice not only protects the driver but also passengers and other road users from the hazards associated with attempting to cross while a train is approaching.