Correct Answer: asthenosphere

Solution : The correct option is asthenosphere .

The upper portion of the mantle is called the "asthenosphere." The asthenosphere is a semi-fluid layer located beneath the rigid lithosphere. It consists of partially molten rock that allows for the movement of tectonic plates.

The earth's crust is the outermost layer of the earth, consisting of solid rock. It includes both the continental crust, which forms the continents, and the oceanic crust beneath the oceans. The crust is relatively thin compared to the other layers of the earth.