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?

Context paragraphs:
Concrete art: Concrete art is an art movement with a strong emphasis on abstraction.  The artist Theo van Doesburg, closely associated with the De Stijl art movement, coined the term "concrete art" as he in 1930 founded the group Art Concret and articulated its features in a manifesto titled "The Basis of Concrete Art", signed by four other artists of the group, including Otto G. Carlsund, Jean Hélion and Leon Tutundjian.  The manifesto explained that the resultant art should be non-referential insofar as its components should "not" refer to, or allude to, the entities normally encountered in the natural, visible world.  This is a distinction from abstraction generally.  In a more general sense "abstract art" could and often does include the "abstraction of forms in nature".  But "concrete art" was intended to emanate "directly from the mind" and consequently to be more "cerebral" than abstract art generally.  Concrete art is often composed of basic visual features such as planes, colors, and forms.  "Sentiment" tends to be absent from concrete art.  The "hand" of the artist may be difficult to detect in finished works of concrete art; concrete art may appear, in some instances, to have been made by a machine.  Concrete art often has a core visual reference to geometry whereas more general abstract art may find its basis in the components of the natural world.  A formulation of a description of concrete art might include a considerable reliance on the formal qualities of an artwork.  Theo Van Doesburg's manifesto stated that art "should receive nothing from nature's formal properties or from sensuality or sentimentality.  We want to exclude lyricism, dramaticism, symbolism, etc…."  In concrete art a mathematical equation can serve as a starting point.  Concrete art can include painting and sculpture.

Johnny Griffin (album): Johnny Griffin (also referred to as J. G., Tenor and Johnny Griffin Quartet) is an album by American jazz saxophonist Johnny Griffin featuring tracks recorded in 1956 and released on the Argo label in 1958.  The album features the first recordings made under Griffin's leadership but was not released until 1958 by which time his first Blue Note album "Introducing Johnny Griffin" (1956) had been released and he had attracted attention as a member of Art Blakey's Jazz Messengers.

Richard Bernstein (artist): Richard Bernstein (October 31, 1939 - October 18, 2002) was an American artist and leading figure in visual arts movement known as pop art.

Andy Warhol: Andy Warhol ( ; born Andrew Warhola; August 6, 1928 – February 22, 1987) was an American artist, director and producer who was a leading figure in the visual art movement known as pop art.  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.  Some of his best known works include the silkscreen paintings "Campbell's Soup Cans" (1962) and "Marilyn Diptych" (1962), the experimental film "Chelsea Girls" (1966), and the multimedia events known as the "Exploding Plastic Inevitable" (1966–67).

Jim Nutt: James T. Nutt (born November 28, 1938) is an American artist who was a founding member of the Chicago surrealist art movement known as the Chicago Imagists, or the Hairy Who.  Though his work is inspired by the same pop culture that inspired Pop Art, journalist Web Behrens says Nutt's "paintings, particularly his later works, are more accomplished than those of the more celebrated Andy Warhol and Roy Lichtenstein."  According to Museum of Contemporary Art curator Lynne Warren, Nutt is "the premier artist of his generation".  Nutt attended the School of the Art Institute of Chicago, in Chicago, Illinois.  He is married to fellow-artist and Hairy Who member Gladys Nilsson.

Lowbrow (art movement): Lowbrow, or lowbrow art, describes an underground visual art movement that arose in the Los Angeles, California, area in the late 1970s.  It is a populist art movement with its cultural roots in underground comix, punk music, and hot-rod cultures of the street.  It is also often known by the name pop surrealism.  Lowbrow art often has a sense of humor – sometimes the humor is gleeful, sometimes impish, and sometimes it is a sarcastic comment.

Jim Evans (artist): Jim Evans, sometimes known as T.A.Z., is an American painter, printmaker, and Creative Director who was a contributing figure in the visual art movement known as underground comics.  After a successful career as a comic illustrator, Jim Evans became known for his work as a painter, poster maker, and owner of the digital design group, Division 13.

The Congregation (Johnny Griffin album): The Congregation is an album by American tenor saxophonist Johnny Griffin recorded in 1957 and released on the Blue Note label.  It would be his last recording for the label.  The cover art was designed by Andy Warhol.

Dennis P. McCann: Dennis P. McCann, born April 14, 1961 in Chicago, Illinois, is an American painter, printmaker, and sculptor, who works primarily in the visual art movement known as pop art.  His works have been featured in a number of publications and exhibitions, and can be found in museums, special collections and galleries throughout America and Europe.  McCann is also a university professor, having held positions at Middle East Technical University, Ankara University and Trakya University, all in the Republic of Turkey.  In 2005, McCann married Turkish artist Fatma Gülnar, and both now reside in Izmir, Turkey.

Julien Friedler: Julien Friedler (born 1950), a writer and contemporary artist, is the leading figure in the visual art movement known as Be art.  Friedler was born in 1950 in Brussels.

Supporting paragraphs: The Congregation (Johnny Griffin album) Andy Warhol
Answer: pop art