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: Feb 15, 1564 saw the birth of what famed Italian physicist, mathematician, astronomer, and philosopher, who discovered the first 4 moons of Jupiter?

Answer: astronomer


Question: What is the smallest country in Central America Costa Rica, Venezuela or El Salvador?

Answer: central america


Question: Abraham Lincoln was president of the Union during the civil war. Who was the president of the Confederate States?

Answer:
american civil war