Which layer is described as a rigid layer made up of the uppermost part of the mantle and the crust?

• A. Mantle
• B. Lithosphere
• C. Crust
• D. Outer Core

Answer: (B)

The rigid outer shell that includes the crust and the rigid upper part of the mantle is the lithosphere. It behaves as a solid, brittle layer that forms the tectonic plates on Earth’s surface. Beneath it lies the asthenosphere, a more ductile region of the mantle that allows these plates to move slowly over it. The other regions don’t fit this description: the mantle as a whole isn’t entirely rigid, the crust alone doesn’t include the mantle portion, and the outer core is liquid and cannot form a rigid shell.