Answer:
a verb os a person place or thing
A simple subject is whom or what the subject is about.
The answer is noun.
The Earth's crust is its lightest, most buoyant rock layer.
The Earth’s mantle is the mostly-solid bulk of Earth's interior.
The asthenosphere is the highly viscous, mechanically weak, and ductile region of the upper mantle of Earth.
The outer core is the third layer of the Earth.
Earth's inner core is the innermost geologic layer of the planet Earth.
