Question: Which American musician, composer, activist and filmmaker whose work is characterized by nonconformity, free-form improvisation, sound experiments and satire of American culture, has collaborated with American keyboard player Tommy Mars?
Sentence (from "Jimmy Greenspoon"): James Boyd "Jimmy" Greenspoon (February 7, 1948 – March 11, 2015) was an American keyboard player and composer, best known as a member of the band Three Dog Night.
Relevant evidence: No