Which composer's music uses "K" before the catalog number?

A function of a work song is to:

A. let workers sing about the misery of their labor B. allow different workers to work at different rates C. remind workers to be loyal to their bosses D. coordinate the rhythm of the workers’ efforts

What is the name given to the kind of art exemplified by Alexander Calder's The Star?

A) ?ready-made B) ?mobile C) ?combine D) ?collage