Could you also say "Hvilken sang lytter du?"
You could say "Hvilken sang lytter du til?"
While I was doing this Duolingo exercise, I was listening to the "Hej, Sokoły!". Y'all should listen to that song right now if you like folk music.
Horer = hear, lytter = listen? So this should translate as: Which song do you hear? And hear is different from listen... Everybody hears a song but not everybody listens to a song!