Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.

Example Input: Which Union leader of the American Civil War gave his name to a tree in California's 'Sequoia National Park'?
Example Output: american civil war

Example Input: The plays 'The Barber of Seville' and 'Marriage of Figaro' were written by whom?
Example Output: the marriage of figaro

Example Input: Edward the Black Prince was the father of which English King?
Example Output:
edward, the black prince