Final answer:
Flares or reflectors are required to mark a disabled commercial motor vehicle on a highway. They must be placed 50 meters behind the vehicle and 50 meters ahead. This ensures that other drivers approaching the disabled vehicle have enough time to see the flares or reflectors and slow down or change lanes to avoid a collision.
Step-by-step explanation:
Flares or reflectors are required to mark a disabled commercial motor vehicle on a highway. They must be placed 50 meters behind the vehicle and 50 meters ahead. This ensures that other drivers approaching the disabled vehicle have enough time to see the flares or reflectors and slow down or change lanes to avoid a collision. By placing them at equal distances on both sides of the vehicle, it provides a clear and consistent warning signal to drivers from all directions.