TASK DEFINITION: Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
PROBLEM: In book and film, which vessel was commanded by Charlie Allnut?

SOLUTION: charlie allnut

PROBLEM: What's the name of Doctor Who's home planet ?

SOLUTION: doctor who

PROBLEM: In which country is the confluence of the White Nile and the Blue Nile?

SOLUTION:
white nile