Final answer:
The lithosphere is composed of the crust and the rigid part of the upper mantle. The crust is the outermost layer of the Earth's surface, while the upper mantle is the part that behaves as a brittle, rigid solid.
Step-by-step explanation:
The lithosphere is composed of the crust and the rigid part of the upper mantle.
The crust is the outermost layer of the Earth's surface. It is a thin, cold, and brittle shell made of rock. The upper mantle is the part of the mantle that behaves as a brittle, rigid solid.
The lithosphere is about 100 kilometers thick and is responsible for earthquakes when stresses act on it and cause it to break.