Question

How do white dwarfs compare with supergiants, in terms of temperature and luminosity? white dwarfs are cooler and have higher luminosity than supergiants. white dwarfs are cooler and have lower luminosity than supergiants. white dwarfs are warmer and have higher luminosity than supergiants. white dwarfs are warmer and have lower luminosity than supergiants.

Answer 1

The answer is ; white dwarfs are warmer and have lower luminosity than supergiants

The reason white dwarfs have lower luminosity is that they are way smaller in size than supergiants, even though their temperatures are way higher in comparison.

White dwarfs and red giants  are formed when the hydrogen fuel at the core of the stars is exhausted. When the star is 1 to 10 solar masses of the sun, then it forms a red  giant.

Answer 2

The correct answer for this question is this one: 
"D. white dwarfs are warmer and have lower luminosity than supergiants." White dwarfs are also more dense than supergiants.
These are the following choices (which quite unclear above)
A. white dwarfs are cooler and have higher luminosity than supergiants.
B. white dwarfs are cooler and have lower luminosity than supergiants.
C. white dwarfs are warmer and have higher luminosity than supergiants.
D. white dwarfs are warmer and have lower luminosity than supergiants.