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: The Brooklyn Bridge crosses which river?

Answer: brooklyn bridge

Question: Charlie Chaplin who died on Christmas Day in 1977, co founded which film studio along with Mary Pickford, Douglas Fairbanks?

Answer: douglas fairbanks

Question: Elaine Page had a top ten hit in 1981 with which song from the musical 'Cats'?

Answer:
cats