Final answer:
Magma is generated by mantle plumes because of decompression melting option b is correct
Step-by-step explanation:
Magma is generated by mantle plumes because of decompression melting. Mantle plumes are thought to be generated at the core-mantle boundary and are regions of increased temperature that can cause the melting of the lithospheric region.
The process of decompression melting occurs when tectonic plates that are diverging cause the underlying region of the mantle to experience reduced pressure conditions. If the mantle is already fairly warm, this decreased pressure may just be enough for magma to be produced.
In cases where tectonic plates converge, and one plate subducts below the other, hydration melting or flux melting can occur due to the release of water from hydrated minerals in the subducting slab. However, the specific generation of magma by mantle plumes in hot spot areas aligns with the concept of decompression melting. option b is correct