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

[Q]: Single-celled organisms and multicellular organisms have this in common: both have a way to get rid of waste materials.
[A]: Which characteristic do single-celled organisms and multicellular organisms have in common?


[Q]: Some materials have negative heats of solution; the dissolution of one of these solutes in water is called?
[A]: Some materials have negative heats of solution; the dissolution of one of these solutes in water is called?


[Q]: The “knee-jerk" motion that people involuntarily perform after being struck in the knee in a certain way is an example of a reflex
[A]:
The “knee-jerk" motion that people involuntarily perform after being struck in the knee in a certain way is an example of what kind of behavior?