What term is used to refer to the Earth's crust?

The term used to refer to the Earth's crust is "lithosphere." This layer encompasses both the crust and the uppermost part of the mantle. The lithosphere is typically rigid and includes the tectonic plates that make up the Earth's surface. It is characterized by solid rock and is where various geological processes, such as the formation of mountains and erosion, take place.

In contrast, the asthenosphere, another layer of the Earth, lies directly beneath the lithosphere and is composed of partially molten rock, which allows for the movement of tectonic plates. The hydrosphere refers to all the water found on or near the Earth's surface, while the mesosphere is associated with the middle layer of the Earth's mantle and the lower part of the atmosphere, not the Earth's crust. Thus, the lithosphere is the correct term to describe the outer solid layer of the Earth.