Slabs of oceanic lithosphere sink at subduction zones because the subducted slab is denser than the underlying asthenosphere. In this process, called , Earth's gravity tugs at the slab, drawing the rest of the plate toward the subduction zone.

The correct option is;

Slab pull

Slabs of oceanic lithosphere sink at subduction zones because the subducted slab is denser than the underlying asthenosphere. In this process, called _Slab pull_, Earth's gravity tugs at the slab, drawing the rest of the plate toward the subduction zone.

Explanation:

A slab pull is the the plunging or subduction of an oceanic plate into the mantle by the force of the weight its weight. This is as a result of the difference in weight per unit volume or densities between the heavier oceanic plate and the hotter, less mantle on which the oceanic plate rests which results in the sinking of the plate into the mantle.

small = small current large mag large current