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

[Q]: Optics explains the behavior of visible light and electromagnetic waves.
[A]: What type of physics explains the behavior of visible light and electromagnetic waves?

[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]: Beer brewers add yeast to the wort to to make alcohol.
[A]:
Why do beer brewers add yeast to the wort?