What is the lithosphere?

• A. Outer layer consisting of the crust and the uppermost part of the mantle; it is strong and rigid and is broken into plates
• B. The liquid iron-nickel core that generates Earth's magnetic field
• C. The boundary between the atmosphere and space
• D. The innermost solid core

Answer: (A)

The lithosphere is the outer, rigid shell of Earth. It consists of the crust plus the uppermost part of the mantle. This layer is strong and brittle, which allows it to break into large pieces called tectonic plates that move very slowly over the partially molten layer beneath.

This distinguishes it from deeper layers: the liquid iron-nickel outer core sits far below and generates Earth’s magnetic field; the boundary between the atmosphere and space is not a physical Earth layer; and the innermost part is the solid inner core.