Answer:
c. The downgoing slab takes along water, and that water lowers the temperature at which rock melts to allow melting in and near the slab.
Explanation:
A subduction zone occurs when one of the plates at convergent boundaries, an area where tectonic plates meet, is an oceanic lithosphere.
These oceanic plates are high in temperature on formation but as they cool, they descend into the mantle below. This descent applies pressure until water is liberated from the lowering crust. The water in turn rises into the surrounding mantle and lowers the temperature at which the rocks melt to produce magma which are partly melted rocks.
This liberation of water from the subducting crust and accompanying melting is responsible for the formation of almost all magma at subduction zones.
