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: Which comedian starred in the ABC sitcom Chicken Soup?

Answer: chicken soup


Question: In which religion is there one god called Ahura Mazda?

Answer: ahura mazda


Question: Agrava, Cephlon and Virn are all fictional planets in which BBC science fiction television series?

Answer:
science fiction on television