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

Q: Pheromones enable communication, which is vital for organisms like ants that live in a large community.

A: Pheromones enable what, which is vital for organisms like ants that live in a large community?
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Q: Most hormones are produced by the endocrine system.

A: Most hormones are produced by which human organ system?
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Q: Iron sulfide iron and sulfur are mixed together in a certain ratio and heated, what do they become.

A:
When iron and sulfur are mixed together in a certain ratio and heated, what do they become?
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