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

Example Input: 'Edward Lewis' and 'Vivian Ward' were the principal characters in which popular 1990 film?
Example Output: edward lewis

Example Input: Which river begins in the Rocky Mountains in south-west Colorado, crosses New Mexico and forms the border between Mexico and the USA before reaching the Gulf of Mexico?
Example Output: new mexico

Example Input: What kind of creature is Bill the Chimney Sweep in Alice in Wonderland?
Example Output:
bill