Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
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Question: Incubation is when birds keep their eggs warm while the embryos inside develop.

Answer: What is it called when birds keep their eggs warm while the embryos inside develop?


Question: Single-celled organisms and multicellular organisms have this in common: both have a way to get rid of waste materials.

Answer: Which characteristic do single-celled organisms and multicellular organisms have in common?


Question: Are cats more active at night than during the day? of the following questions is testable in a scientific investigation.

Answer:
Which of the following questions is testable in a scientific investigation?