Question: The cover art for Johnny Griffin's album "The Congregation" was by an American artist who was a leading figure in the visual art movement known as what?
Sentence (from "Andy Warhol"): His works explore the relationship between artistic expression, celebrity culture, and advertising that flourished by the 1960s, and span a variety of media, including painting, silkscreening, photography, film, and sculpture.
Relevant evidence: No