How Are White Dwarfs Treated in the Luminosity Class Definitions

Multiple Choice

How are white dwarfs treated in the luminosity class definitions?

A) They are considered a subgroup of main sequence stars, class Vb.
B) They are class VI.
C) They are not given a classification because they have not yet begun to produce energy by nuclear fusion.
D) They are not given a classification because they no longer create energy by nuclear fusion.