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

[EX Q]: Brenda Mae Tarpley achieved fame under what name?
[EX A]: brenda mae tarpley

[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]: Which city stands at the confluence of the Sava and Danube rivers?
[EX A]:
sava