Which of the control lights visible in the illustration informs you that the main beam lights are enabled?

The illustration shows three warning lights: A - an orange headlamp with rays crossed by a wavy line (rear fog light), B - a blue headlamp with horizontal rays, C - a green headlamp with rays pointing downwards and crossed by a wavy line (front fog lights). The blue light B tells you that the main beam is on - answer B.

The Regulation on the technical conditions of vehicles requires a vehicle to have an indicator signal for the main beam - a light signal, not flashing, blue in colour. It is the only blue warning light among the lighting lamps, so you cannot confuse it: the lights for sidelights, dipped headlights and front fog lights are green, and the one for rear fog lights is yellow. The horizontal rays on the symbol show that the beam goes straight and far, so it dazzles drivers coming from the opposite direction. That is why the Road Traffic Act allows you to use main beam only from dusk to dawn on unlit roads and requires you to switch to dipped headlights when a vehicle is approaching from the opposite direction, and also when you could dazzle the driver of the vehicle in front of you. The blue light is there to remind you that you are using "full beam" - when you see it in town or in a line of cars, switch your lights.

Legal basis: Annex No. 6 to the Regulation on the technical conditions of vehicles and the scope of their necessary equipment; Art. 51 para. 3 of the Road Traffic Act (Prawo o ruchu drogowym)