Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
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Question: Who died of a burst appendix after being punched in the stomach?

Answer: appendicitis


Question: 'Dookie' and '21st. Century Breakdown' are albums by which American rock band?

Answer: 21st century breakdown


Question: In which opera does Wagner's Bridal Chorus (popularly known as Here comes the bride) feature?

Answer:
bridal chorus