Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.

[EX Q]: Besides the Caucasus, what mountain range forms the border of Europe and Asia?
[EX A]: asia

[EX Q]: Physics. What is the SI unit for amount of substance?
[EX A]: amount of substance

[EX Q]: Which insect is responsible for transmitting the bubonic plague?
[EX A]:
bubonic plague