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

[EX Q]: Radioactivity is the release of particles and/or energy from the nucleus of an atom.
[EX A]: What is the release of particles and/or energy from the nucleus of an atom described as?

[EX Q]: Transparent matter transmits light without scattering it.
[EX A]: What type of matter transmits light without scattering it?

[EX Q]: You call egg-shaped galaxies, which are reddish to yellowish in color because they contain mostly old stars, elliptical galaxies.
[EX A]:
What do you call egg-shaped galaxies, which are reddish to yellowish in color because they contain mostly old stars?