Question: Operalia, The World Opera Competition, helped launch the career of Bulgarian operatic soprano who was born on what day?

Context paragraphs:
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.

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.

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.

Guanqun Yu: Guanqun Yu (; born 1982) is a Chinese soprano who has sung in opera houses and concert halls internationally.  In 2008 she won the Belvedere International Singing Competition and in 2012 she placed 2nd in the Operalia, The World Opera Competition.  She is particularly known for portraying heroines in the operas of Wolfgang Amadeus Mozart, Giacomo Puccini, and Giuseppe Verdi.

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".

Liao Changyong: Prof. Liao Changyong (; born October 25, 1968), sometimes referred in Western media as C. Y. Liao or Changyong Liao, is a Chinese operatic baritone and academic.  He won first prize in three different international competitions in 1996 and 1997: the Operalia, The World Opera Competition; the French International Toulouse Singing Competition; and the Queen Sonja International Music Competition.  While his performance career has mainly been in China, he has appeared as a guest artist with opera companies and orchestras internationally.  He is the head of the voice department at the Shanghai Conservatory of Music.

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.

Ao Li: Ao Li (born 8 February 1988) is a Chinese operatic bass-baritone and voice teacher who is particularly known for his performances at the San Francisco Opera.  In 2013 he won first prize in the Operalia, The World Opera Competition and in 2014 he won the Metropolitan Opera National Council Auditions.

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.

Sonya Yoncheva: Sonya Yoncheva (Bulgarian: Соня Йончева, born 25 December 1981) is a Bulgarian operatic soprano.

Supporting paragraphs: Operalia, The World Opera Competition Sonya Yoncheva
Answer: born 25 December 1981