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

Example Input: To which actress is Daniel Craig married?
Example Output: daniel craig

Example Input: Which TV character has sisters called Daisy and Rose?
Example Output: daisy

Example Input: What is the name of the Towers in which Doctor Who villain Kroagnon (The Great Architect) existed as a disembodied intelligence stored in a tank?
Example Output:
doctor who