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

Example Input: What canal opened in Egypt?
Example Output: egypt

Example Input: The rivers Axe, Brue, Cary, Parrett, eta, are in which English county?
Example Output: castle cary

Example Input: At the battle of Ashdown, in A.D 871, the Danes were defeated by forces under which famous king?
Example Output:
battle of ashdown