The movement of heavy elements toward Earth's centre was related to which force?

Correct answer: Gravity

The direct answer is C: gravity. During the early development of Earth, materials were heated and partly melted. Gravity caused dense, heavy elements such as iron and nickel to move downward toward the centre, while lighter materials remained nearer the outer layers. This separation is called differentiation and helped form Earth’s layered structure: a dense metallic core, a mantle and a lighter crust. Option C is correct because gravity attracts mass toward the centre of a large body. Option A, “magnetic light,” is not a recognised force or process in planetary differentiation. Option B is wrong because evaporation changes liquid into vapour; it does not sort heavy elements into Earth’s core. Option D is wrong because wind erosion acts at the surface and cannot move materials through the whole early Earth to its centre. The reasoning chain is: heating and melting allowed movement; density differences separated materials; gravity pulled the denser materials inward. Memory cue: heavy elements sink, light elements rise—gravity builds the core.