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

Example Input: Aragon and Castile joined to form which country?
Example Output: aragon

Example Input: What horse won the 2009 Grand National?
Example Output: 2009 grand national

Example Input: Invented by Alexander Parkes in about 1856 and originally called Parkesine, what was the first thermo-plastic?
Example Output:
alexander parkes