The correct option is C, the inner core.
How many layers does the earth has?
Earth has distinct layers: the solid, rigid crust with moderate temperatures; the semi-fluid, slowly flowing mantle with moderate to high temperatures; the liquid outer core with extremely high temperatures; and the solid inner core with even higher temperatures.
The layer of Earth that is solid and extremely hot is the innermost layer, known as the "inner core." The inner core is primarily composed of iron and nickel, and despite its high temperature, it remains solid due to the immense pressure at that depth.
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