Question: Who did Luis Gianneo teach, who became considered a chief exponent of Argentine folk music?
Context: This is a list of operas by Argentine composers.  Argentina's first native born opera composer was Francisco Hargreaves (1849-1900) who composed "La gatta bianca" (1875) and "Los estudiantes de Bologna" (1897), followed by Zenón Rolón (1856-1902) who composed several operas as well as operettas and zarzuelas.  The works of many of the composers from this generation were first performed outside Argentina.  Native Argentine opera was to develop much more with the massive European (mainly Italian) immigration in the late 19th century and even more with the opening of the Teatro Colón in 1908 where most of the 20th century operas listed here had their world premieres.  Some of the first operas to treat Argentine subjects or national themes were Arturo Berutti's "Pampa" (1897) based on the life of Juan Moreira and "Yupanki" (1899) based on the life of Inca warrior Manqu Inka Yupanki.  Also notable in this genre were Felipe Boero's "Tucumán" (1918) set during the Battle of Tucumán and "El matrero" (1929).  Considered by many to be the quintessential Argentine opera, "El matrero" had a libretto based on gaucho folk tradition and incorporated Argentine folk melodies and a traditional gaucho dance.  The Spanish playwright Federico García Lorca was also the inspiration for several Argentine operas.  His plays, "La zapatera prodigiosa" and "Bodas de sangre", were the basis of operas by Juan José Castro, while Osvaldo Golijov's 2003 opera "Ainadamar" is based on events in the playwright's life. Ariel Ramírez (4 September 1921 – 18 February 2010) was an Argentine composer, pianist and music director.  He was considered "a chief exponent of Argentine folk music" and noted for his "iconic" musical compositions. Luis Gianneo (1897–1968) was an Argentine composer, pianist and conductor.  As music educator, he was the teacher of composers Ariel Ramirez, Juan Carlos Zorzi, Virtú Maragno, Pedro Ignacio Calderón and Rodolfo Arizaga, among others. The folk music of England is traditionally based music, which has existed since the later medieval period.  It is often contrasted with courtly, classical and later commercial music.  Folk music has been preserved and transmitted orally, through print and later through recordings.  The term is used to refer to English traditional music and music composed, or delivered, in a traditional style.  English folk music has produced or contributed to several important musical genres, including sea shanties, jigs, hornpipes and dance music, such as that used for Morris dancing.  It can be seen as having distinct regional and local variations in content and style, particularly in areas more removed from the cultural and political centres of the English state, as in Northumbria, or the West Country.  Cultural interchange and processes of migration mean that English folk music, although in many ways distinctive, has particularly interacted with the music of Scotland.  It has also interacted with other musical traditions, particularly classical and rock music, influencing musical styles and producing musical fusions, such as British folk rock, folk punk and folk metal.  There remains a flourishing sub-culture of English folk music, which continues to influence other genres and occasionally to gain mainstream attention. Argentine rock (locally Rock nacional) is rock music composed or made by Argentine bands or artists mainly in the Spanish language.  For nearly half a century it has been a major popular genre, and is regarded as part of the music tradition of Argentina alongside tango and Argentine folk music. 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> Marta Lambertini (born 13 November 1937) is an Argentine composer.  She was born in San Isidro, Buenos Aires, and studied at the Universidad Catolica Argentina with Roberto Caamano, Luis Gianneo and Gerardo Gandini, graduating in 1972.  She continued her studies in electroacoustic music in Buenos Aires, at the Centro de Investigationes de la Ciudad with Francisco Kröpfl, Gerardo Gandini, José Maranzano and Gabriel Brncic. Turkish folk music ("Türk Halk Müziği") combines the distinct cultural values of all civilisations that have lived in Turkey and its former territories in Europe and Asia.  Its unique structure includes regional differences under one umbrella.  It was the most popular music genre in the Ottoman Empire era.  After the foundation of the Turkish Republic, Atatürk asked to make a wide-scale classification and archiving of samples of Turkish folk music from around the country, which was launched in 1924 and continued until 1953 to collect around 10,000 folk songs.  In the 1960s, Turkish folk music met with radio and folk musicians like Aşık Veysel, Neşet Ertaş, Bedia Akartürk became the most popular names of the Turkish folk music.  In the 1970s and 1980s, with the rising popularity of arabesque and Turkish light western, Turkish folk music has lost some ground, but singers like Belkıs Akkale, İzzet Altınmeşe, Selda Bağcan, Güler Duman and Arif Sağ made successful hit songs and became important representatives of the genre. Contemporary folk music refers to a wide variety of genres that emerged in the mid 20th century and afterwards which were associated with traditional folk music.  Starting in the mid-20th century a new form of popular folk music evolved from traditional folk music.  This process and period is called the (second) folk revival and reached a zenith in the 1960s.  The most common name for this new form of music is also "folk music", but is often called "contemporary folk music" or "folk revival music" to make the distinction.  The transition was somewhat centered in the US and is also called the American folk music revival.  Fusion genres such as folk rock, folktronica, and others also evolved within this phenomenon.  While contemporary folk music is a genre generally distinct from traditional folk music, it often shares the same English name, performers and venues as traditional folk music; even individual songs may be a blend of the two. Haydée Mercedes Sosa (] ; 9 July 1935 – 4 October 2009), sometimes known as La Negra (literally: "The Black One"), was an Argentine singer who was popular throughout Latin America and many countries outside the region.  She was born on Argentina's Independence Day.  With her roots in Argentine folk music, Sosa became one of the preeminent exponents of nueva canción.  She gave voice to songs written by many Latin American songwriters.  Her music made people hail her as the "voice of the voiceless ones", and "the voice of America".
Answer: Ariel Ramírez