Who can tell me the meanings of these?
minimalism
impressionism
primitivism
serialism
and how are they different in the twentieth century music?

Minimalism is music that is often repetitive with very short phrase, something like Work by Rihanna. 
Impressionism is a style of composition with harmonic effects, using a whole-tone scale, similar to Let It Go by James Bay.
Primitivism develops regular tones of music into new ideas and forms of music, similar to the richness of using Romanticism, listen to Don't Hurt Me by Jeremih.
Serialism uses  series of techniques and methods to create different music elements, like Bodak Yellow by Cardi B.

Iwould go with write exactly two extra paragraphs to point out additional information. but the keyword "exactly" throws me off. leads me to believe it's d. go with your gut feeling. either "write exactly two extra paragraphs" or "none of these".