7. according to the theory of isostasy, which statement must be true? a. the asthenosphere is denser than the lithosphere. b. the asthenosphere has the same density as the lithosphere. c. the lithosphere has the same density as the core. d. the lithosphere is denser than the asthenosphere.

A. The astenosphere is denser than the lithosphere

Explanation:

The theory of isostasy is a theory that suggest that the layers of Earth are arranged in accordance to their density. It is a theory that usually refers to the mantle and crust. The mantle (astenosphere) is denser than the crust (lithosphere), so the crust floats on top of it, depending on its density, with he continental crust being higher, while the oceanic crust being lower. The two forces that are responsible for this are the gravity and buoyancy.