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

Q: Resistors connected end to end are said to be in series.

A: Resistors connected end to end are said to be in what?
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Q: The endocrine system produces hormones to regulate growth, development, and reproduction.

A: Which human organ system produces hormones to regulate growth, development, and reproduction?
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Q: Sample part of an experiment or other investigation consists of the individuals or events that are studied.

A:
What part of an experiment or other investigation consists of the individuals or events that are studied?
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