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

Example Input: The novels 'The Shipmaster, 'The Iron Ships' and 'The Trade Winds' by Cyril Abraham, are based on which 1970's British tv series?
Example Output: cyril abraham

Example Input: Which Nation does Aston Villa Goalkeeper Brad Guzan represent?
Example Output: brad guzan

Example Input: The Ambassador Bridge, which connects the US with Canada, spans which river?
Example Output:
united states