If the Surface Temperatures of White Dwarf Stars Are 4

Multiple Choice

If the surface temperatures of white dwarf stars are 4 times that of the Sun, and energy output per unit area of a star depends on the fourth power of the temperature by the Stefan-Boltzmann relation, why are white dwarfs intrinsically so faint?

A) White dwarfs are very small.
B) White dwarfs have very thin atmospheres that do not emit continuum radiation but only line emissions, like a low-density gas.
C) White dwarfs are shrouded in very thick atmospheres.
D) White dwarfs are moving rapidly away from the Sun and their spectra are extremely redshifted, hence they appear faint at visible wavelengths.