Final answer:
A hot mantle plume is typically found under a divergent plate boundary, where tectonic plates move apart leading to magma formation due to reduced pressure in the mantle.
Step-by-step explanation:
A hot mantle plume is commonly associated with a divergent plate boundary. Divergent boundaries are where tectonic plates are moving apart, and this movement leads to reduced pressure in the mantle beneath, often resulting in the production of magma. These plumes can originate from the core-mantle boundary and create a hotspot, which can lead to the melting of the lithospheric region. Convergent and transform boundaries have different processes and outcomes. Convergent boundaries involve the subduction of one plate beneath another, potentially creating magma from the hydration of minerals and subsequent melting due to increased temperatures. Transform boundaries, where plates slide past each other, typically have shallow earthquakes but do not produce magma as there is no direct mechanism for melting.
Overall, while hotspots can occur under any type of plate boundary, they are most notably associated with divergent boundaries where the creation of magma is more directly linked to the reduced pressure from the separating plates.