Discuss the roles that gravity played in earth's accretion and subsequent differentiation, and describe how gravity interacted with other processes (e. g., impact heating, radioactive decay, and liquid immiscibility) to give rise to the planet's internal structure

Accretion or what is known as a gravity-driven process formed the planet Earth. This process causes gravitational attraction of material in the vicinity of the solar disk to the growing Earth. The process carries on with meteorite impacts and gravity interacted with impact heating. This formed the Earth's internal structure or the molten core. 

The answer might be c.