What describes the movement of plates at a subduction zone?

At a subduction zone, one tectonic plate moves under another and sinks into the mantle. This process occurs due to the differences in density between the colliding plates; typically, an oceanic plate, which is denser, is forced beneath a less dense continental plate or another oceanic plate. The sliding of one plate below the other leads to the formation of geological features such as deep ocean trenches and volcanic arcs. This process is a critical part of the Earth’s tectonic activity and significantly influences geological events like earthquakes and volcanic eruptions.

The other options describe different tectonic activities. For example, stationary plates do not account for the dynamic nature of plate tectonics, while pulling apart describes divergent boundaries where plates move away from each other. The collision leading to crust formation typically relates to continental-continental convergence, where neither plate subducts but rather crumples to form mountain ranges.