Which layer of Earth is composed of solid rock, including both continental and oceanic crust?

The lithosphere is the layer of Earth that consists of solid rock, encompassing both the continental and oceanic crust. This layer extends from the surface down to a depth of about 100 kilometers (approximately 62 miles) and includes the rigid upper part of the mantle as well as the crust itself. The lithosphere is vital because it forms the tectonic plates that move and interact at their boundaries, leading to geological phenomena such as earthquakes, volcanic eruptions, and mountain formation.

In contrast, the atmosphere is the gaseous layer surrounding Earth, crucial for weather and climate but not composed of solid rock. The core is primarily made up of iron and nickel and is divided into a solid inner core and a liquid outer core. The mesosphere, which lies beneath the lithosphere in the mantle, is characterized by semi-solid rock that can flow but is not classified as solid rock like the lithosphere. Therefore, the lithosphere is the correct choice, as it specifically refers to the solid outer layer of Earth containing both types of crust.