Which part of the mantle is made off soft rock?

Lithosphere

Asthenosphere

Outer core

Lower mantel

Mostly Iron and some small amounts of nickel, sulfur and oxygen. The "weak sphere" - is the soft layer of the mantle where pieces of the lithosphere move. It is made of solid rock that flows like putty. Beneath the asthenosphere, the strong lower part of the mantle is the "middle sphere

Outer core is the answer because mantle dissolved at one time