When parking on the highway, how far must you be visible from either end?

Answer: B — 15 meters

When parking on the highway, it is essential to ensure that your vehicle is visible to other drivers from a considerable distance to prevent accidents and ensure safety. The requirement to be visible from 15 meters at either end is designed to provide a clear line of sight for approaching vehicles, allowing them to react appropriately to your parked vehicle. This distance helps to prevent collisions, as it gives sufficient warning to other drivers about the presence of your vehicle, especially on busy roads where speed may be high. Ensuring a 15-meter visibility distance contributes to safer travel conditions for all road users, making it the correct answer.