a piece's "subject matter" refers to the

a.  symbols in an abstract work of art.

b.  content that comes from the objects or events in the image.

c.  shapes in nonrepresentational paintings.

d.  materials an artist used to create the piece.

B. content that comes from the objects or events in the image.

Explanation:

the answer is counterpoint.

counterpoint definition: "the art or technique of playing a melody or melodies in conjunction with another, according to fixed rules."

counterpoint is present in a lot of baroque music- such as bach (notably his wtc prelude and fugues) and scarlatti, but can also be found in music by mozart, beethoven. it can even be found in music as modern as john williams!