What layer is made up of mostly silicon and oxygen and exists as a semi-fluid
layer of partly molten rock?

lithosphere

The lithosphere is mostly liquid, with some medium-density materials, such as silicon. The lithosphere is more plastic and flows slowly compared to the solid crust of Earth. The lithosphere includes the core and the lower portion of the mantle. The lithosphere includes the crust and the uppermost portion of the mantle, which is sold and rigid.

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i think the answer is b.

c. live where it’s cold and icy