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 had hits with Stepping Out and Different For Girls?

Answer: different for girls


Question: In 2013 Yahoo purchased which pictures and video microblogging website business that was founded in 2007 in New York City by David Karp?

Answer: yahoo!


Question: The Big Muddy River in Southern Illinois joins which other river?

Answer:
missouri river