Question: Knoxville: Summer of 1915 is a work for voice and orchestra by what American composer of orchestral, opera, choral, and piano music, who is one of the most celebrated composers of the 20th century?

Context paragraphs:
Knoxville: Summer of 1915: Knoxville: Summer of 1915, Op.  24, is a 1947 work for voice and orchestra by Samuel Barber, with text from a 1938 short prose piece by James Agee.  The work was commissioned by soprano Eleanor Steber, who premiered it in 1948 with the Boston Symphony Orchestra under Serge Koussevitzky.  Although the piece is traditionally sung by a soprano, it may also be sung by tenor.  The text is in the persona of a male child.

Stephen Paulus: Stephen Paulus (August 24, 1949 – October 19, 2014) was a Grammy winning American composer, best known for his operas and choral music.  His best-known piece is his 1982 opera "The Postman Always Rings Twice", one of several operas he composed for the Opera Theatre of St. Louis, which prompted "The New York Times" to call him "a young man on the road to big things".  His style is essentially tonal, and melodic and romantic by nature.  He received grants from the National Endowment for the Arts and Guggenheim Foundation and won the prestigious Kennedy Center Friedheim Prize.  He was commissioned by such notable organizations as the Minnesota Opera, the Chamber Music Society of Lincoln Center, Opera Theatre of Saint Louis, the Saint Louis Chamber Chorus, the American Composers Orchestra, the Dale Warland Singers, the Harvard Glee Club and the New York Choral Society.  Paulus was a passionate advocate for the works and careers of his colleagues.  He co-founded the American Composers Forum in 1973, the largest composer service organization in the U.S., and served as the Symphony and Concert Representative on the ASCAP Board of Directors from 1990 until his death (from complications following a stroke in July 2013) in 2014.

Carlos Guastavino: Carlos Guastavino (April 5, 1912 - October 29, 2000) was one of the foremost Argentine composers of the 20th century.  His production amounted to over 500 works, most of them songs for piano and voice, many still unpublished.  His style was quite conservative, always tonal and lusciously romantic.  His compositions were clearly influenced by Argentine folk music.  His reputation was based almost entirely on his songs, and Guastavino has sometimes been called "the Schubert of the Pampas."  Some of his songs, for example "Pueblito, mi pueblo", "La rosa y el sauce" ("The Rose and the Willow") and "" ("The Dove Was Wrong"), became national favorites.  Unlike most other composers, at any time or place, Guastavino earned enough from his royalties and performing rights that he really had little need for other income. <ref name="BkltNI5818/20">MacDonald, Callum.  Essay in booklet with the recording "Carlos Guastavino: The Complete Piano Music", Martin Jones, piano.  Nimbus, NI 5818/20 (2008). </ref>

Emmanuel Chabrier: Alexis Emmanuel Chabrier (] ; January 18, 1841September 13, 1894) was a French Romantic composer and pianist.  Although known primarily for two of his orchestral works, "España" and "Joyeuse marche", he left an important corpus of operas (including "L'étoile"), songs, and piano music.  He was admired by composers as diverse as Debussy, Ravel, Richard Strauss, Satie, Schmitt, Stravinsky, and the group of composers known as Les six.  Stravinsky alluded to "España" in his ballet "Petrushka"; Gustav Mahler called "España" "the beginnings of modern music" and alluded to the "Dance Villageoise" in the "Rondo Burleske" movement of his Ninth Symphony.  Ravel wrote that the opening bars of "Le roi malgré lui" changed the course of harmony in France, Poulenc wrote a biography of the composer, and Richard Strauss conducted the first staged performance of Chabrier's incomplete opera "Briséïs".

Vassil Kazandjiev: Vassil Kazandjiev ] (or Vasil Ivanov Kazandzhiev Bulgarian: Васил Иванов Казанджиев ) (born September 10, 1934) is a Bulgarian composer of orchestral, chamber, vocal, film and piano music.  His work is representative of the 20th century classical music and 21st century classical music.

Victor Herbert: Victor August Herbert (February 1, 1859 – May 26, 1924) was an Irish-born, German-raised American composer, cellist and conductor.  Although Herbert enjoyed important careers as a cello soloist and conductor, he is best known for composing many successful operettas that premiered on Broadway from the 1890s to World War I.  He was also prominent among the tin pan alley composers and was later a founder of the American Society of Composers, Authors, and Publishers (ASCAP).  A prolific composer, Herbert produced two operas, a cantata, 43 operettas, incidental music to 10 plays, 31 compositions for orchestra, nine band compositions, nine cello compositions, five violin compositions with piano or orchestra, 22 piano compositions and numerous songs, choral compositions and orchestrations of works by other composers, among other music.

Samuel Barber: Samuel Osborne Barber II (March 9, 1910 – January 23, 1981) was an American composer of orchestral, opera, choral, and piano music.  He is one of the most celebrated composers of the 20th century: music critic Donal Henahan stated that "Probably no other American composer has ever enjoyed such early, such persistent and such long-lasting acclaim."

George Lynn (composer): George Lynn (1915 – March 16, 1989) was an American composer, conductor, pianist, organist, singer, and music educator.  A longtime member of the American Society of Composers, Authors and Publishers, his compositional output encompasses more than 200 orchestral and choral pieces; many of which have been performed by major American symphony orchestras like the Denver Symphony, the American Symphony Orchestra under Leopold Stokowski, and the Philadelphia Orchestra.  He taught on the music faculties of several prominent American colleges, notably conducting several university choirs.  Throughout his life he was active as a conductor, organist, and pianist for various church and community choirs.

Carlos Duarte: Carlos Duarte (born in Caracas on June 1, 1957; died April 13, 2003) was a Venezuelan composer and pianist.  His premier recital was at age 11 and at 16 he won a national award for composition (He obtained the prize for 3 consecutive years from 1973 to 1975).  He composed some pieces for piano and orchestra: "Ludios" (Ludus), "Sinfonietta La Mar" (Sea Sinfonietta), "Concierto de la Canción Triste" (Sad Song Concerto) and "Requiem para un Idiota" (Requiem for an Idiot).  In 1999 he composed a Quintet for the End of the Century (Quinteto para el Fin del Siglo).  The composer himself performed the first performances in the same year, with the Arpeggione Quartet (as a Piano Quintet) and the European Union Chamber Orchestra (as a Concerto for Piano and String Orchestra).  His last work was a Requiem, entitled "Requiem para un Idiota" (Requiem for an Idiot), for Piano (as his own voice), Chorus, 8 Clarinets, 8 Bassons, 8 Contrabassoons and 8 Double Basses.  The Caracas Municipal Symphony Orchestra (Orquesta Sinfónica Municipal de Caracas) posthumously premiered in April 30th, 2006 under the baton of Rodolfo Saglimbeni and Arnaldo Pizzolante playing the piano part.  Both are among the closest friends of Duarte.  He composed also the incidental piano music for "Jav & Jos", "The Last Minotaur" and "Clitemnestra" all of them performed by the "Theja" Theater Group in the nineties.  Between 1987 and 1990 he was the Pianist of the Caracas Municipal Symphony Orchestra.  He served as a professor at the Universidad Simón Bolívar Post-Graduate Music Faculty.

Bruno Bjelinski: Bruno Bjelinski (born Bruno Weiss; 1 November 1909 – 3 September 1992) was one of a most influential Croatian composers in the 20th century.  He was extremely prolific as a composer.  His unique musical style was built upon the music of Poulenc, Hindemith, Ravel and Milhaud.  He developed his own and recognizable musical language with the elements of neoclassicism.  Bjelinski composed six operas, three ballets, 15 symphonies, 2 cello concertos, a cantata, piano music, songs, chamber music, and concertos for piano, violin, viola, bassoon, flute, and piano duo.  He also composed music for the Croatian football movie "Plavi 9".

Supporting paragraphs: Knoxville: Summer of 1915 Samuel Barber
Answer: Samuel Osborne Barber II