Answer: c. represent the mafic materials present in the magma
Explanation:
Fractional crystallization is a rock formation process whereby early forming crystals settle at the bottom of the magma chamber and the magma at the top loses its mineral components thereby becoming more felsic in the process.
The components of the magma determine how much reaction can occur as silica is important to catalyzing these reactions. The crystals formed at the beginning of these series of reactions represent the mafic materials in the magma but are more mafic that the magma .