Terrestrial Planets Are Thought to Have Dense Iron Cores Because

Multiple Choice

Terrestrial planets are thought to have dense iron cores because

A) the accumulation of material into planets in the original solar system nebula would have begun with the heavier elements,to be followed later by lighter materials.
B) magnetism in iron would be sufficiently powerful to pull more iron into the center of the forming planet.
C) thermonuclear processes produced iron in the earlier phases of planetary formation.
D) in earlier molten states,the heavy elements sank and lighter materials floated to the surface by chemical differentiation.