Question: Sextet was by the Polish composer who has completed how many operas?

Context articles: String Sextet (Waterhouse)
Karol Szymanowski
Paweł Łukaszewski
Polish Requiem
Gaetano Fraschini
Krzysztof Penderecki
Sebastian z Felsztyna
Adam Sztaba
Sextet (Penderecki)
Armida (Mysliveček)

String Sextet, Op.
 1, is a string sextet in four movements by Graham Waterhouse.
 While the composer began the work as one movement in 1979, he completed it in four movements in 2013.
 The completed version was first performed at the Gasteig in Munich on 9 February 2014.
Karol Maciej Szymanowski (] ; 6 October 188229 March 1937) was a Polish composer and pianist, the most celebrated Polish composer of the early 20th century.
 He is considered a member of the late 19th-/early 20th-century modernist movement Young Poland and widely viewed as one of the greatest Polish composers.
Paweł Łukaszewski is a Polish composer of choral music.
 He has won seven prestigious Fryderyk Awards.
 According to David Wordsworth, Łukaszewski is the best-known Polish composer of his generation in and out of Poland "by far" (Wordsworth 2013, p. 50).
Polish Requiem (original Polish title: Polskie Requiem; German: "" ), also A Polish Requiem, is a large-scale requiem mass for soloists, mixed choir and orchestra by the Polish composer Krzysztof Penderecki.
 The Lacrimosa, dedicated to the trade union leader Lech Wałęsa, was written for the unveiling of a statue at the Gdańsk shipyards to commemorate those killed in the Polish anti-government riots in 1970.
 He expanded the work into a requiem, writing other parts to honour different patriotic events over the next four years.
 The "Polish Requiem" was first performed in Stuttgart on 28 September 1984.
 Penderecki revised and expanded the work in 1993, and expanded it again in 2005 with the additional movement, Ciaccona .
 It is called "Polish Requiem" because its parts are dedicated to heroes and victims of Polish history.
 One of the better-known works by Penderecki, the mass largely follows the liturgical Latin of the requiem format with the addition of "Święty Boże ", the Polish translation of the Trisagion.
Gaetano Fraschini (16 February 1816 – 23 May 1887) was an Italian tenor.
 He created many roles in 19th century operas, including five composed by Giuseppe Verdi.
 His voice was "heroic ... with a baritonal quality, ... yet Verdi and Donizetti appreciated his ability to sing softly and with subtlety."
 An Italian biographer has pointed out Fraschini's role in extending the longevity of Donizetti's operas, while at the same time accelerating the ascent of Verdi's repertory.
 He was indeed the most prominent singer who facilitated the transition from Donizetti to Verdi.
 Fraschini sang over one hundred roles and Verdi placed him at the top of his favorite tenors' list and described him as a "natural Manrico" for his "Il trovatore".
 Fraschini also played a pivotal role in the success of many operas by Pacini and Mercadante.
Krzysztof Eugeniusz Penderecki ( ; ] ; born 23 November 1933) is a Polish composer and conductor. "
The Guardian" has called him Poland's greatest living composer.
 Among his best known works are his "Threnody to the Victims of Hiroshima", "Symphony No. 3", "St. Luke Passion", "Polish Requiem", "Anaklasis", "Utrenja", four operas, eight symphonies and other orchestral pieces, a variety of instrumental concertos, choral settings of mainly religious texts, as well as chamber and instrumental works.
Sebastian z Felsztyna (also Sebastian de Felstin, Sebastian Herburt) (c. 1480/1490?
 – after 1543) was a Polish composer and music theorist, regarded as the greatest Polish composer of the early 16th century.
Adam Sztaba (born 15 February 1975) is a Polish composer, music producer, conductor, arranger and pianist.
 He graduated in composition from Fryderyk Chopin Music Academy (now University of Music).
 He collaborated with many Polish and international stars such as: Caro Emerald, Quincy Jones, Sting, Chris Botti, Michael Bolton, José Carreras, Kenny G, Dolores O'Riordan, Ewa Malas-Godlewska, Jose Cura, Lemar, NDR Bigband, Ive Mendes, Lutricia McNeal, Dita von Teese, Helena Vondráčková, Karel Gott, Drupi, Edyta Gorniak, Maryla Rodowicz, Kayah, Ania Dabrowska, Sinfonia Varsovia, Polish Radio Symphony Orchestra.
 He made his debut at age 18 music for the musical "Mirage?"
.
 In 2003, together with Tomasz Filipczak, composed the music for the first Polish show dance "Opentaniec".
 In 2005 he founded the Adam Sztaba Orchestra.
 He was the musical director, arranger and conductor of many well-known television programs, including "Idol" (Polish edition), SOPOT FESTIVAL 2005 and 2006, "Dancing With the Stars" (Polish edition of "Strictly Come Dancing").
 In 2008 he was director of the Academy of the television program "Star Academy" (Polish edition).
 Recently he composed and recorded music for the film "From Full To Full".
 In September 2010 he was music director of the inauguration of the European Special Olympic Games 2010 in Warsaw.
 In December 2010 he performed with Sting and conducting the Polish Radio Symphony Orchestra in a concert to celebrate the 85th anniversary of Polish Radio.
 In July 2011 he was a music director of the concert on the occasion of the beginning of Poland's EU Presidency and performed with Chris Botti, Dolores O'Riordan, Michael Bolton and Kenny G.
 He was a juror in the Polish edition of the TV show "Must Be The Music".
 In 2016 he was musical director and conductor of the World Youth Day 2016 in Krakow, the musical highlight of which was the concert titled "Credo in Misericordiam Dei" with almost 2 million pilgrims attending.
The Sextet is a two-movement composition for clarinet, horn, violin, viola, cello, and piano by Polish composer Krzysztof Penderecki.
 The composition was written in 2000 and is, according to some critics, the composer's most substantial chamber work to date.
Armida is an opera in three acts by Josef Mysliveček set to a libretto by Giovanni Ambrogio Migliavacca based on an earlier libretto by Philippe Quinault.
 It is one of many operas set at the time of the Crusades that is based on characters and incidents from Torquato Tasso's epic poem "La Gerusalemme liberata".
 This opera (and all the rest of Mysliveček's operas) belong to the serious type in Italian language referred to as "opera seria".
 It incorporates many elements from the operatic "reform" movement of the 1770s, including short vocal numbers and short choruses incorporated into the fabric of the drama and lavish use of accompanied recitative.