How far must you stop from a railroad crossing when the lights are flashing?

Answer: B — At least 15 feet

When approaching a railroad crossing with flashing lights, it is essential to stop at least 15 feet away from the tracks. This distance is specified to ensure that your vehicle is safely clear of the crossing while allowing enough room for trains to pass. Stopping at this distance not only keeps you and other road users safe from potential collisions with trains, but also ensures that you have a clear view of the tracks to gauge whether it is safe to proceed once the lights stop flashing. The safety regulations governing this practice emphasize the importance of being vigilant around railroad crossings, as trains can approach quickly and are often harder to see than other vehicles.