Answer
a. Divergent boundaries are characterized by outpourings of basaltic lava.
b. The source of these lavas is the underlying mantle.
c. The source rocks melt due to decompression melting caused by the upward movement of the mantle material. As the lithosphere stretches and thins at divergent boundaries, the decrease in pressure lowers the melting point of the mantle rocks, leading to their partial melting and the generation of basaltic magma.
Work Step by Step
Refer to the above answer.
