Question: The unfinished opera Modest Mussorgsky was written by a man who was a member of numeric group.
Context: "The Fair at Sorochyntsi" is the first story in the collection "Evenings on a Farm Near Dikanka" by Ukrainian-born writer Nikolai Gogol.  Later in the 19th-century the story was adapted as an opera of the same name by Modest Mussorgsky (left unfinished by the composer, and completed by other hands). The Fair at Sorochyntsi (Russian: Сорочинская ярмарка , "Sorochinskaya yarmarka", "Sorochyntsi Fair") is a comic opera in three acts by Modest Mussorgsky, composed between 1874 and 1880 in St. Petersburg, Russia.  The composer wrote the libretto, which is based on Nikolai Gogol's short story of the same name, from his early (1832) collection of Ukrainian stories "Evenings on a Farm near Dikanka".  The opera remained unfinished and unperformed at Mussorgsky's death in 1881. Vyacheslav Lavrent'yevich Nagovitsin (Russian: Вячеслав Лаврентьевич Наговицин ) is a Russian composer born in Magnitogorsk (21 December 1939).  He was a student of Dmitri Shostakovich at the Leningrad Conservatory that he graduated in 1966 (postgraduate school, he graduated from the undergraduate school of the Conservatory in 1963).  In 1963-1964 he worked in "Ulan-Ude Opera and Ballet Theater".  In 1966-1970 he was a lecturer at the Mussorgsky Musical School in Leningrad.  In 1968-1970 he also worked as the Music Director of the Leningrad Comedy Theatre.  Since 1970 he became a professor at the Leningrad Conservatory.  He orchestrated two unfinished operas of Modest Mussorgsky: Zhenitba and Salammbô.  His orchestration of Salammbô was used by Valery Gergiev at the Mérida festival in 1991. Boris Godunov (Russian: Борис Годунов , "Borís Godunóv") is an opera by Modest Mussorgsky (1839–1881).  The work was composed between 1868 and 1873 in Saint Petersburg, Russia.  It is Mussorgsky's only completed opera and is considered his masterpiece.  Its subjects are the Russian ruler Boris Godunov, who reigned as Tsar (1598 to 1605) during the Time of Troubles, and his nemesis, the False Dmitriy (reigned 1605 to 1606).  The Russian-language libretto was written by the composer, and is based on the drama "Boris Godunov" by Aleksandr Pushkin, and, in the Revised Version of 1872, on Nikolay Karamzin's "History of the Russian State". Mussorgsky (Russian: Мусоргский , "Musorgskiy " ) is a 1950 Soviet biopic film directed by Grigori Roshal, about the emergence of Russian composer Modest Mussorgsky.  It was entered into the 1951 Cannes Film Festival. Khovanshchina (Russian: Хованщина ) is a 1959 Soviet film, released the following year, directed by Vera Stroyeva and based on the eponymous opera by 19th-century Russian composer Modest Mussorgsky.  For his adaptation of Mussorgsky's score, Dmitri Shostakovich was nominated for an Academy Award for Scoring of a Musical Picture.  The music was conducted by Evgeny Svetlanov. Salammbô (Russian: Саламбо, "Salambo" [alternative title: The Libyan (Russian: Ливиец, "Liviyets" )]) is an unfinished opera in 4 acts by Modest Mussorgsky.  The fragmentary Russian language libretto was written by the composer, and is based on the novel "Salammbô" (1862) by Gustave Flaubert, but includes verses taken from poems by Vasiliy Zhukovsky, Apollon Maykov, Aleksandr Polezhayev, and other Russian poets. Zhenitba (Russian: Женитьба , "Zhenit'ba", "Marriage") is an unfinished opera begun in 1868 by Modest Mussorgsky to his own libretto based on Nikolai Gogol's comedy "Marriage".  This 1842 play is a satire of courtship and cowardice, which centres on a young woman, Agafya, who is wooed by four bachelors, each with his own idiosyncrasies. Khovanshchina (Russian: Хованщина , "Hovánščina", sometimes rendered The Khovansky Affair; since the ending -ščina is pejorative) is an opera (subtitled a 'national music drama') in five acts by Modest Mussorgsky.  The work was written between 1872 and 1880 in St. Petersburg, Russia.  The composer wrote the libretto based on historical sources.  The opera was unfinished and unperformed when the composer died in 1881. Modest Petrovich Mussorgsky (Russian: Моде́ст Петро́вич Му́соргский ; ] ; 21 March [O.S. 9 March] 1839 – 28 March [O.S. 16 March] 1881 ) was a Russian composer, one of the group known as "The Five".  He was an innovator of Russian music in the romantic period.  He strove to achieve a uniquely Russian musical identity, often in deliberate defiance of the established conventions of Western music.
Answer: The Five