The lithosphere is:

A) also called the crust
B) also called the mantle
C) the rigid portion of the Earth crust and upper mantle)
D) where convection occurs in the mantle

Lithosphere

The rigid outer layer of the Earth, encompassing the crust and the uppermost part of the mantle.

Crust

The outermost solid layer of Earth, consisting of continental and oceanic crust.

Upper Mantle

The layer of the Earth located beneath the Earth's crust and above the lower mantle, characterized by its semi-fluid asthenosphere and more rigid upper part.