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: Billy the Kid was a native of which US state?

Answer: billy

Question: Baltusrol Course lies in which US state?

Answer: baltusrol golf club

Question: At which narrow pass did Leonidas and 300 Spartans fight to the death, in order to slow down the Persian army?

Answer:
battle of thermopylae