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.