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

[EX Q]: In which country did the dance The Czardas originate?
[EX A]: csardas

[EX Q]: In 1864, the Dale Dyke Dam burst while being filled, leading to the death of 240 people in which British city?
[EX A]: dale dike reservoir

[EX Q]: What is the dam in the Black Canyon of the Colorado River on the border between the US states of Arizona and Nevada that was completed in 1935?
[EX A]:
black canyon of the colorado