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

[Q]: Soft of these best describes the way a feather feels.
[A]: Which of these BEST describes the way a feather feels?

[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]: Neutron stars are the corpses of left over supernova explosions.
[A]:
Neutron stars are the corpses of left over what?