What is form?
a. the arrangement of visual elements in a work of art.
b. what is being represented in the piece.
c. the visible elements of a piece.
d. the sense of harmony between parts and the whole.

I personally think its D the sense of harmony between parts and the whole because it just makes sense

The linear perspective changed the quality of art because it gave art a sense of reality. it gave the illusion that the background and surroundings were actually close and/or far and a sense of depth. linear perspective change the quality of art following its birth the renaissance period as they want the art to be more realistic and they believe one way to achieve it is to use the method of linear perspective. it uses the principle of math to realistically portray space and depth in art. 

Contemporary jazz is sometimes called smooth jazz