In what situation can you use the emergency lights if the tram is equipped with one?

The question is about hazard warning lights in a tram that is equipped with them. You should use them to signal the presence of a tram that is at a standstill because of a breakdown - answer C.

Hazard warning lights warn other road users that a vehicle is stationary in a place where it would not usually stop and is an obstacle. The Road Traffic Act requires drivers to signal that a power-driven vehicle is at a standstill. Formally, a tram is not a power-driven vehicle, but the tram driver applies this rule accordingly, because a tram at a standstill is an obstacle in the same way. Trams built since 2000 have hazard warning lights. A normal stop at a tram stop (answer B) is expected and does not require hazard warning lights. Using them to say thank you for letting you through (answer A) is not provided for in the rules and may mislead others.

Legal basis: Art. 3 para. 1 and Art. 50 (applied accordingly) of the Road Traffic Act (Prawo o ruchu drogowym); § 14 para. 1 point 11 of the Regulation of the Minister of Infrastructure of 2 March 2011 on the technical conditions of trams and trolleybuses and the scope of their necessary equipment (Dz.U. nr 65 poz. 344)