Final answer:
The lithosphere is the solid, rigid layer comprised of the Earth's crust and the uppermost mantle, responsible for supporting tectonic plates and causing earthquakes and volcanic eruptions.
Step-by-step explanation:
The solid, rigid layer of rock that houses the tectonic plates and is responsible for earthquakes and volcanic eruptions is known as the lithosphere. This layer is comprised of the crust and the uppermost part of the mantle, which are both brittle and rigid, making them break under stress, leading to seismic activities. Distinct from the lithosphere, the mantle is a vast middle layer made of solid yet deformable rock.
The Earth's core is composed of the inner and outer core, with the inner core being solid and the outer core being liquid. These various layers are defined and differentiated by their physical and mechanical properties as well as their chemical compositions.