The rocky outer layer of Earth that includes mountains is called the crust.

Here's why:

* Crust: The Earth's outermost layer, relatively thin compared to the other layers. It's divided into oceanic crust (thinner and denser) and continental crust (thicker and less dense).

* Mountains: Mountains are formed by geological processes like tectonic plate collisions, volcanic activity, and erosion. These processes occur within the Earth's crust.

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