Answer: d. Sounds
Explanation:
According to Bruno Netti on Ethnomusicology, Music is diverse. It always expresses a subtext determined by culture, class, gender and personality and by a society's idea of music. Evidenced by the different genres of music we have.
Alan Merriam's three part model on music suggests that music is a phenomenon that consists of three sides; sound, behaviour and ideas.
So therefore for music to be understood, it should be studied as a group of sounds, as behaviour that leads to these sounds, and as a group of ideas or concepts that govern the sound and the behaviour.
The answer would be D because silk doesn't shink