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

[Q]: Collision theory states that chemical reactions occur when atoms, ions, or molecules collide.
[A]: What states that chemical reactions occur when atoms, ions, or molecules collide?


[Q]: Tornadoes can occur in any.
[A]: At what time of the year can tornadoes occur?


[Q]: The best way humans can conserve water is to use less.
[A]:
What's the best way humans can conserve water?