TASK DEFINITION: Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
PROBLEM: Christian Grey is a character in what recent book trilogy?

SOLUTION: christian grey

PROBLEM: Which country mainly makes up the Horn of Africa?

SOLUTION: africa

PROBLEM: Which golfer won his second major title when he won the 2015 Open Championship?

SOLUTION:
2015 open championship