Earth's 3 principal layers that are divided into:
 A. Crust, Upper Mantle, Lower Mantle, Liquid Outer Core, and Solid Inner Care
 B. Crust, Upper Mantle, Corona, Radiative Zone, Core O 
C. Crust, Upper Mantle, Lower Mantle, Mid-Atlantic Ridge, East Pacific Rise 
D.  Crust, Subduction Zone, Convergent Boundary, Solid Inner Core