I believe it would refer to intelligence quotient.
I would have to say it's part of the theme.
Morality and politics is the ethos of the story, aka origin aka theme.
With-out a theme there would be no plot...and no setting.
So...
C. Theme
Answer:
A. there is a universal song in nature which all hearts can hear
Explanation:
the artist is saying there is always a song, no matter the circumstances.
