In this task, you're given an open-domain question. Your task is to provide an answer to the given question. There is only one unique answer for each question. Your answer should be short, and refer to an entity, date, number, etc. Do not put your answer in the context of a sentence.

Q: Where does the tree of life come from?

A: many of the world's mythologies, religious and philosophical traditions
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Q: Who's the little girl that played in waterworld?

A: Tina Marie Majorino
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Q: When did earth's population reached 6 billion?

A:
12 October 1999
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