Question: As a child, Olga Peretyatko sand in the children's choir of a theatre that opened in what year?
Sentence (from "Mariinsky Theatre"): The Mariinsky Theatre (Russian: Мариинский театр , Mariinskiy Teatr, also spelled Maryinsky or Mariyinsky) is a historic theatre of opera and ballet in Saint Petersburg, Russia.
Relevant evidence: No