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: In which bay is Alcatraz?

Answer: alcatraz island


Question: Who was the father of Edward the Elder, the Anglo-Saxon King from 899 to 924?

Answer: edward the elder


Question: Which city state led the beaten Greek forces at the Battle of Thermopylae?

Answer:
battle of thermopylae