What is the primary composition of the lithosphere?

The primary composition of the lithosphere is solid rock and minerals. The lithosphere encompasses the rigid outer layer of the Earth, which includes the crust and the uppermost portion of the mantle, extending down to a depth of about 100 kilometers (62 miles). This layer is characterized by its solid state, primarily composed of igneous, metamorphic, and sedimentary rocks, as well as various minerals.

Understanding the lithosphere is crucial in the study of plate tectonics, as it is the layer that is broken into tectonic plates that float on the more ductile asthenosphere beneath it. This rigidity allows the lithosphere to maintain its structure and support landforms, unlike the other options that refer to substances not primarily associated with the lithosphere: gaseous elements do not form a solid structure, liquid water is part of the hydrosphere, and magma is a molten substance found below the Earth's surface but not in the lithosphere itself. Thus, solid rock and minerals accurately describe the lithosphere's composition and provide the foundation for various geological processes.