Answer:
c. metals are heavier than rocky material and the metals sank to the core when the Earth was molten.
Explanation:
When the sun formed after the collapse of a large giant molecular clouds (GMC) it caused an immense generation of heat and pushed away most of the low-density materials, but heavier elements remained. This heat vaporized the material around the sun.
The heating resulted in the formation of melted zones where high density elements melted and moved towards the core. This resulted in the planetary differentiation of Earth.