Mechanical weathering
a.
breaks apart rocks by physical processes
b.
occurs when chemical reactions dissolve or change the minerals in rocks
c.
occurs when iron is exposed to oxygen and water
d.
none of the above

A.the process of breaking big rocks into little ones

The answer is b im not sure 

Magma forms by partial melting of upper mantle and crust. partial melt means that only a fraction of the available material forms a melt, and that the remainder stays solid. the partial melt rises because of its lower density and ascends through he crust. this is so conclusive mean the answer would be magma igneous rocks or balistic magma.