Which of the following control lights indicates that the high-beam lights are on?

The blue headlight symbol with straight, horizontal lines visible under the letter C is the standardised indicator light informing that the high-beam headlights are on. According to the regulations on the technical conditions of vehicles, switching on high beams must be signalled to the driver by such a blue indicator light. The other symbols mean respectively: A – hazard warning lights, B – sidelights.