What is the required minimum and maximum stopping distance for a bus at a railroad crossing with no clearly marked stop line?

The correct answer outlines the required minimum and maximum stopping distance for a bus approaching a railroad crossing without a clearly marked stop line, specifying the need to stop no closer than 15 feet and no further than 50 feet from the nearest rail. This distance is crucial for ensuring safety, as it allows the driver to have an adequate view of the tracks while also maintaining a safe distance from trains that could be approaching.

Stopping at this specified distance provides the driver a better vantage point to observe any trains that may be coming and reduces the risk of accidents at crossings where visibility might be limited. The distance requirements also account for the length and speed of trains, allowing enough room for the bus to remain clear of the tracks until it is safe to proceed.

In regards to the other options, their specified distances either do not offer sufficient space for safety or exceed the ideal stopping point, which could potentially result in risky situations.