How are white dwarfs and neutron stars similar?

a. they are both main sequence stars.

b. they are both left over after a star has died. a white dwarf is left over from the death of a low-mass star and a neutron star from the death of a high-mass star.

c. white dwarfs are made of carbon, and so are neutron stars.

d. they both will explode in a supernova when they have died.