TASK DEFINITION: Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
PROBLEM: Besides the Caucasus, what mountain range forms the border of Europe and Asia?

SOLUTION: asia

PROBLEM: In which US state are the Catskill Mountains?

SOLUTION: catskill mountains

PROBLEM: In 2014 where is artist Ai Weiwei based?

SOLUTION:
ai weiwei