Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Q: Thermosphere is the upper-most atmosphere.

A: What is the upper-most atmosphere known as?
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Q: Cell -> tissue -> organ -> organ system sequence represents the correct levels of organization for multicellular organisms.

A: Which sequence represents the correct levels of organization for multicellular organisms?
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Q: Two tributaries come together at a(n) confluence.

A:
Where do two tributaries come together at?
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