The driver of a commercial motor vehicle must stop within how many feet of railroad tracks?

Answer: D — 15-50 feet

A commercial motor vehicle driver must stop within 15 to 50 feet of railroad tracks. This distance allows the driver to ensure a clear view of both directions of the tracks, which is essential for safely crossing them. Stopping too close or too far away can increase the risk of a collision with an oncoming train. It is crucial for commercial vehicle drivers to follow this requirement to prevent accidents and ensure the safety of themselves and others on the road.