Q: Determine the topic of the question. Question: "what is metformin used for?" Topic:
A: Metformin

Q: Determine the topic of the question. Question: "who kill franz ferdinand ww1?" Topic:
A: Assassination of Archduke Franz Ferdinand of Austria

Q: Determine the topic of the question. Question: "how many professional hockey teams in canada?" Topic:
A: National Hockey League

Q: Determine the topic of the question. Question: "who replaced nikita khrushchev?" Topic:
A:
Nikita Khrushchev