The process of forming the iron - rich core, the low density crust which is also rich in silicon, oxygen, aluminum, and the intermediate density mantle rich in silicon, oxygen, and magnesium is called the differentiation. Thus, the answer to this item is letter A.
The chemical layers of Earth are formed from the process called differentiation during planetary accretion. The Earths three main chemical layers are the core, crust, and the mantle.
