MOSTost Comet Nuclei Are Believed to Be

MOSTost comet nuclei are believed to be:

A) carbonaceous chondrite meteorites-carbon material-ignited by sunlight and resulting in long smoke trails.
B) pieces of dusty ice left over from the formation of the solar system.
C) pieces of dirty ice ejected from the surface of the icy satellites of the outer planets by asteroid impacts.
D) pieces of rock or iron chipped from asteroids by impacts.