Which of earth's mechanical layers is most easily deformed?
a. lower mantle
b. crust
c. lithosphere
d. asthenosphere

Asthenosphere, one of the earth's mechanical layers is most easily deformed.

Option D.

Explanation:

The layer named Asthenosphere is the one which can easily be deformed due to its semi solid (mostly fluid) state. It is often regarded by Geologists that, the asthenosphere is the weakest of all the other layers of Earth.

According to Plate Tectonic theory, the Continental plates float over this layer, hence they often collide with each other giving rise to physical features. The other layers like, Crust, Core and the Mantle are relatively strong and are not easily destructible when compared to Asthenosphere.