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

Example Input: Albion is the oldest known name for which nation?
Example Output: albion

Example Input: Which is the largest continent on Earth?
Example Output: earth

Example Input: The 1942 film, Casablanca was based on which play, written by Joan Alison and Murray Burnett?
Example Output:
casablanca