12. Which layer of the Earth makes up the asthenosphere? a. Crust
b. Mantle
C. Outer core
d. Inner core

The answer is The mantle

Explanation:

The asthenosphere (from the Greek word asthenēs meaning “weak”) is a mechanically weak layer consisting of the lower portion of the upper mantle, extending down to 660 km. Contrary to popular belief, it is not a “sea of molten rock”. The upper mantle is actually composed of an Mg- and Fe-rich rock called peridotite.

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answer at the divergent plate boundary in the middle of the ocean;