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Question
Black dwarfs areA) very common, making up the majority of the dark matter in the universe.
B) often made from very low mass protostars that never fuse hydrogen.
C) rare, for collapsing cores of over three solar masses are uncommon.
D) rare, for few binary systems are close enough for this merger to happen.
E) not found yet; the oldest, coldest white dwarf in the Galaxy has not cooled enough yet.
Answer
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