TASK DEFINITION: Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
PROBLEM: What's the name of Doctor Who's home planet ?

SOLUTION: doctor who

PROBLEM: Which engineer built the Menai Suspension Bridge and the Caledonian Canal?

SOLUTION: menai suspension bridge

PROBLEM: Benjamin Britten's last opera. Death in Venice, is based on a 1912 short story by which author?

SOLUTION:
death in venice