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

[EX Q]: Water and humidity is the critical factor for the survival of segmented worms.
[EX A]: What is the critical factor for the survival of segmented worms?

[EX Q]: If two populations do not mate and produce fertile offspring, separate species result.
[EX A]: If two populations do not mate and produce fertile offspring, what results?

[EX Q]: Hormones generally travel through the circulatory system system of the body.
[EX A]:
Through what system of the body do hormones generally travel?