How far must all vehicles stop from the nearest rail of a railroad crossing when a train is approaching?

The correct response indicates that vehicles must stop between 15 and 50 feet from the nearest rail of a railroad crossing when a train is approaching. This regulation is in place to ensure the safety of drivers and passengers by providing enough distance to avoid potential collisions with trains. Stopping at this distance allows for adequate visibility of the train and ensures that vehicles are far enough away from the tracks to minimize risks, especially considering the speed at which trains can travel.

The specified range of 15 to 50 feet is significant because it accommodates various circumstances, such as the speed of the train and the driver's ability to see along the tracks. Stopping too close could lead to danger if a train is coming, while stopping too far could lead to misunderstanding of the safe stopping distance.

In contrast, the other options do not comply with recommended safety practices. Distances shorter than 15 feet can be too close to allow for adequate reaction time and visibility, especially in areas where multiple tracks may exist. Therefore, adherence to the specified stopping range is crucial for ensuring the safety of all road users near railroad crossings.