What phenomenon is responsible for hot spots a. mantle plumes b. pyroclastic flow c. ridge push subduction

The phenomenon is responsible for hot spots is Mantle Plumes.

Explanation:

Volcanic activity that is completely unrelated to the plate movements or boundaries and takes place within the tectonic plates is termed as hotspot volcanism. Mantle plumes are basically the lighter and warmer mass inside the mantle that comes up as a result of the process of convection.

It has a head like a bulb followed by a long tail. When the head reaches the lithosphere, it spreads out like a mushroom. During this process, the pressure drops down while the temperature stays constant resulting in decompression melting of the mantle, producing huge amounts of magma.