Which process is involved in the natural recycling of Earth's crust through subduction and sea-floor spreading?

The process involved in the natural recycling of Earth's crust through subduction and sea-floor spreading is known as the tectonic cycle. This cycle encompasses the movements of the Earth's lithospheric plates, which are continually being created, destroyed, and transformed over geological time.

Subduction occurs when one tectonic plate is forced beneath another, leading to the recycling of crustal material back into the mantle. This process not only contributes to the formation of deep ocean trenches and volcanic arcs, but also plays a crucial role in the long-term evolution of the Earth's crust. On the other hand, sea-floor spreading occurs at mid-ocean ridges, where new crust is formed as magma rises to the surface, pushing older crust away from the ridge.

In contrast, while the rock cycle illustrates how rocks are formed, broken down, and reformed through processes like weathering, erosion, and sedimentation, it does not specifically target the movement of tectonic plates or the mechanisms of crustal recycling. The hydrological cycle focuses on the movement of water through the Earth's systems, and the carbon cycle examines the flow of carbon among the atmosphere, hydrosphere, lithosphere, and biosphere. Therefore, the tectonic cycle is the most appropriate choice to describe the