Which of the following best describes the lithosphere according to plate tectonic theory?

The lithosphere is best described as being made up of major and minor plates. This component of the Earth's structure includes the crust and the uppermost part of the mantle, which together form the rigid outer layer of the Earth. The lithosphere is divided into tectonic plates that float on the semi-fluid asthenosphere beneath. These plates can interact in various ways, leading to geological phenomena such as earthquakes, volcanic activity, and mountain-building processes.

While the lithosphere includes a variety of rock types, it is not solely composed of igneous rock, and it is not a liquid layer nor does it exist underneath the crust; instead, it encompasses the entire crust and the upper mantle. This understanding is fundamental in the study of plate tectonics and how these interacting layers shape the Earth's surface.