What is “perimeter lighting” according to traffic regulations?

1. A A yellow lighting system arranged around an oversize freight. The distance between lamps should not exceed 100 cm.
2. B Green lights installed on the sides of long vehicles.
3. C A portable lighting system that has a chain on which flags are installed. The minimum distance between the flags should be 50 cm.
4. D A fixed lighting system on the walls of long vehicles.