What is a slab pull?

Slab pull refers to the process related to the movement of tectonic plates, specifically the action of a denser, subducting tectonic plate being pulled into the mantle due to its own weight. As one tectonic plate sinks and subducts beneath another, the gravitational force plays a significant role, effectively pulling the plate down into the Earth's mantle. This process is a key driver of plate tectonics and contributes to various geological phenomena, including the formation of deep ocean trenches and volcanic arcs.

The other choices outline different mechanisms related to plate tectonics but do not accurately define slab pull. Tectonic push at divergent boundaries, for instance, refers to the forces that push plates apart; processes involving magma might involve different types of tectonic or volcanic activity rather than the specific action of a subducting plate; and the rise of hot mantle plumes describes a process that typically results in hotspot volcanism, not directly related to the sinking motion of plates. Thus, the definition of slab pull directly aligns with understanding the gravitational influence on subducting plates, making it the correct choice.