Question: Who is a Bulgarian operatic soprano that had their career launched by The World Opera Competition? 

full_context: Document 1: Galina Savova: Galina Savova (Bulgarian: Галина Савова ) (born 1945) is a Bulgarian operatic soprano. The singer completed her education first in Varna, in Sofia and then began her career in 1966 with a beginner's engagement at the National Opera House of the Bulgarian capital. She sang there already lots from the Slavic and the Italian operatic repertoire, as it was set in 1971 at a guest performance of the Opera of Sofia at the Paris Grand Opera in the title role of Puccini's "Turandot".
Document 2: Operalia, The World Opera Competition: Operalia, The World Opera Competition is an annual international competition for young opera singers. Founded in 1993 by Plácido Domingo, the competition has helped launch the careers of several important artists, such as Joseph Calleja, Giuseppe Filianoti, Rolando Villazón, José Cura, Joyce DiDonato, Elizabeth Futral, Inva Mula, Ana María Martínez and Sonya Yoncheva.
Document 3: Bogdan Volkov: Bogdan Volkov is a Russian operatic tenor. Born in Ukraine, one of the most young talented tenors of his generation. He is the winner of second prize at Plácido Domingo’s Operalia, The World Opera Competition in Guadalajara, Mexico in 2016 and first prize at the Paris Opera Competition in 2015.
Document 4: Kamen Tchanev: Kamen Tchanev (Bulgarian: Камен Чанев ) (27 August 1964 Sliven, Bulgaria) is a Bulgarian tenor. In 1991 he graduated the Bulgarian State Music Academy Pancho Vladigerov and in 1992 he studied in the Boris Hristov Music Academy in Rome. Two years later – in 1994 he was one of the winner in the International Competition Jussi Bjorling. Kamen Tchanev performed in many opera houses in Bulgaria, Czech Republic (since 1997 he is frequent guest in the Prague State Opera), France, Switzerland, Sweden, Italy, Romania and South Korea. Since 1993 Kamen Tchanev is soloist of the Sofia National Opera. Recordings for the Bulgarian National Radio, RAI-2, Italy and in 1999 he recorded with Plovdiv Philharmonic Orchestra, Nayden Todorov conducting a CD production for the American label MMO.
Document 5: Vanya Milanova: Vanya Milanova was born on January the 12th 1954. She is an internationally renowned solo violinist and recording artist. She is noted for being a female breakthrough artist in a male dominated field. Her beauty of tone, technical ability and having an unusually large repertoire have been much commentated on in press reviews. She has made a lasting impact on violin performing through being the very first woman to record the entire 24 Paganini caprices in a primarily male field for the Simax Label, Oslo, 1985. She performed works which were often only attributed to male soloists. Bulgarian born, Vanya Milanova was a child prodigy, having performed her first paid concert at the age of three. She studied at the Music School in Sofia and the State Music Academy in Sofia in the class of Peter Arnaudov and later at the Guildhall School of Music in London where she studied with pedagogue Yfrah Neaman OBE. Before turning 20 years of age she had already won prizes at many of the major competitions: Tchaikovsky, Queen Elizabeth and Paganini. She has played with some of the best orchestras in England, France, Italy, Turkey, Israel, Portugal, Sweden, Norway, Denmark, South America and South Africa. She has made frequent recordings with the BBC – London and Manchester, Norwegian Label Simax and the Italian Label Real Sound. and has played at the Royal Festival Hall, Wigmore Hall, the Royal Albert Hall and the Royal Opera House for the Edward Boyle Memorial Concert 1983 attended by Her Royal Majesty the Queen in aid of the Edward Boyle Memorial Trust, featuring Vanya Milanova, the Amadeus String Quartet, Murray Perahia, Kathryn Scott and Dame Janet Baker). Vanya Milanova has been awarded 'Freedom of the City Award' in her native Bulgaria for her outstanding contribution to music and popularising classical music to a younger generation. Alongside being a performing and recording artist, She was violin professor at Bilkent University, Turkey and at various other institutions where she disseminated her style to a new generation of young violinists.
Document 6: Plácido Domingo discography: Plácido Domingo has made hundreds of opera performances, music albums, and concert recordings throughout his career as an operatic tenor. From his first operatic leading role as Alfredo in "La traviata" in 1961, his major debuts continued in swift succession: "Tosca" at the Hamburg State Opera and "Don Carlos" at the Vienna State Opera in 1967; "Adriana Lecouvreur" at the Metropolitan Opera, "Turandot" in Verona Arena and "La bohème" in San Francisco in 1969; "La Gioconda" in 1970; "Tosca" in Royal Opera House, Covent Garden in 1971; "La bohème" at the Bavarian State Opera in 1972; "Il trovatore" at the Paris Opéra in 1973 and "Don Carlo" at the Salzburg Festival in 1975, "Parsifal" in 1992 at the Bayreuth Festival; and the list continues until today; the same role is often recorded more than once.
Document 7: Repertoire of Plácido Domingo: Spanish tenor Plácido Domingo has officially sung 147 roles in Italian, French, German, English, Spanish and Russian. His main repertoire however is Italian ("Otello", Cavaradossi in "Tosca", "Don Carlo", Des Grieux in "Manon Lescaut", Dick Johnson in "La fanciulla del West", Radames in "Aida"), French ("Faust", "Werther", Don José in "Carmen", Samson in "Samson et Dalila"), and German ("Lohengrin", "Parsifal", and Siegmund in "Die Walküre"). Domingo currently continues to add more operas to his repertoire. Since 2009, he has moved substantially into the baritone repertoire, especially focusing on Verdi baritone roles. In 2015, he made his most recent debuts as Macbeth at the Berliner Staatsoper, Don Carlo in "Ernani" at the Metropolitan Opera, and Gianni Schicchi at the Los Angeles Opera. Tim Page, a Pulitzer Prize-winner for music criticism, described Domingo in a 1996 "Washington Post" article as "the most versatile, intelligent and altogether accomplished operatic tenor now before the public."
Document 8: Ghena Dimitrova: Ghena Dimitrova (Bulgarian: Гeна Димитpова ) (6 May 1941 – 11 June 2005) was a Bulgarian operatic soprano. Her voice was known for its power and extension used in operatic roles such as Turandot in a career spanning four decades.
Document 9: Andrea Carroll (soprano): Andrea Carroll is an American soprano who has had an active international career in concerts and operas since 2012. A finalist in the 2015 Operalia, The World Opera Competition, she is particularly known for her performances with the Houston Grand Opera and the Vienna State Opera.
Document 10: Plácido Domingo: José Plácido Domingo Embil, {'1': ", '2': ", '3': ", '4': "} (] ; born 21 January 1941), known as Plácido Domingo, is a Spanish tenor, conductor and arts administrator. He has recorded over a hundred complete operas and is well known for his versatility, regularly performing in Italian, French, German, Spanish, English and Russian in the most prestigious opera houses in the world. Although primarily a "lirico-spinto" tenor for most of his career, especially popular for his Cavaradossi, Hoffmann, Don José, and Canio, he quickly moved into more dramatic roles, becoming the most acclaimed Otello of his generation. In the early 2010s, he transitioned from the tenor repertory into almost exclusively baritone parts, most notably Simon Boccanegra. He has performed 147 different roles.
Document 11: José Iturbi International Music Competition: The José Iturbi International Music Competition is a music competition named after the Spanish piano virtuoso José Iturbi. It was established by the José Iturbi Foundation in 2007 and takes place at the University of California Los Angeles. The competition has two tracks: one for pianists and the other for opera singers. The competition is open to pianists and singers of all nationalities between the ages of 17 and 35. The competition's co-founder, Donelle Dadidgan, is the founder of the Hollywood Museum and the goddaughter of José Iturbi. Initially held annually from 2007 to 2010, the next competition was scheduled in 2013.
Document 12: Stefka Evstatieva: Stefka Evstatieva (Bulgarian: Стефка Евстатиева ) (born 7 May 1947) is a Bulgarian operatic soprano. Born in Ruse, she studied voice at the State Academy of Music in Sofia with Elena Kisselova. She began her career with the Ruse Opera where she made her debut as Amelia in "Un ballo in maschera" and sang there from 1971 to 1979. In 1974 Stefka Evstatieva won the second prize at the International Tchaikovsky Competition in Moscow. (No first prize was awarded). In 1978 she won the Grand Prize of Belgian Radio & TV Belcanto Competition; in 1979 Grand Prize and Golden Ring in the Young Singers Competition in Sofia; and in 1982 the Best Performance Award at the Arena di Verona.
Document 13: Sonya Rostova: Sonya Rostova is a character in Leo Tolstoy's 1869 novel "War and Peace", and in Sergey Prokofiev's 1955 opera "War and Peace" and Dave Malloy's 2012 musical "Natasha, Pierre & the Great Comet of 1812" based on it. She is the orphaned niece of Count and Countess Rostov.
Document 14: Sonya Yoncheva: Sonya Yoncheva (Bulgarian: Соня Йончева, born 25 December 1981) is a Bulgarian operatic soprano.
Document 15: Krassimira Stoyanova: Krassimira Stoyanova (Красимира Стоянова ) (born in Veliko Tarnovo, 16 August 1962) is a Bulgarian soprano. She is particularly well known for the title role in "La Juive". She was awarded the Austrian title of Kammersängerin in 2009.
ground_truth: Sonya Yoncheva