(Solved): URGENT The diagram below shows a C-O convergent boundary similar to ones you have drawn before. This ...

The diagram below shows a C-O convergent boundary similar to ones you have drawn before. This one represents the western margin of South America. The diagram shows three areas where partial melting occurs, indicated by light cross-hatching and pink shading. Magma rises from location A, pools in a magma chamber at location B in the continental crust, and then magma rises from this location, pools again in a magma chamber between $B$ and the surface (also in the continental crust), and finally magma erupts from this uppermost magma chamber onto the surface as a lava flow. It is safe to assume the lava erupted on the surface has a different composition than the magma produced by partial melting at location A. Describe two different ways in which the lava's composition could have been produced. You must provide an explanation of these processes - not just the names - to earn credit.