What Is the Similarity in Physical Principle Between the Mechanism

What is the similarity in physical principle between the mechanism at work in an emission nebula and that in a household fluorescent light bulb?

A) Both depend on atomic ionization and subsequent recombination of atoms to produce light, mainly in specific spectral lines.
B) The spectral lines they produce from hydrogen gas are the same in both the nebula and the fluorescent tube.
C) Both depend on heating of a neutral gas to produce a continuum spectrum.
D) Both depend on electrical energy to heat a gas; in a fluorescent bulb electric energy comes from the household supply, whereas in the emission nebula electrical energy arises from rapid motion of ionized gases.