TASK DEFINITION: Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
PROBLEM: Basil Rathbone made 14 Sherlock Holmes films. Who played the part of Dr Watson?

SOLUTION: watson

PROBLEM: Who directed the film Black Swan (in ballet)?

SOLUTION: black swan

PROBLEM: Sheppey and Canvey are islands in which English river estuary?

SOLUTION:
canvey island