Question: Yvonne Mounsey, the South African-American ballet dancer was known for the important roles she created in the works of which choreographer who co-founded the New York City Ballet?
Sentence (from "George Balanchine"): George Balanchine (born Giorgi Melitonovich Balanchivadze; January 22, 1904April 30, 1983) was a choreographer.
Relevant evidence: No