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

Example Input: The Bob Dylan songs 'Desolation Row', 'Tombstone Blues' and 'Like A Rolling Stone' featured on which album?
Example Output: tombstone blues

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

Example Input: What was the computer's name in 2001: A Space Odyssey?
Example Output:
2001: a space odyssey