Here's why:

* Lithosphere: This is the rigid outermost layer of the Earth, consisting of the crust and the uppermost part of the mantle.

* Hydrosphere: This encompasses all the water on Earth, including oceans, lakes, rivers, and groundwater.

* Atmosphere: This is the layer of gases that surrounds the Earth.

* Biosphere: This refers to all living organisms on Earth, including plants, animals, and microorganisms.

The crust, being the solid, rocky outer layer of the Earth, fits squarely within the definition of the lithosphere.