Answer :

The Mantle. 
The crust is the outside land part, the mantle is the lava part that the crust floats on, and the outer and inner core are more solid metals.

C. OUTER CORE-- made of liquid metals. The mantle is solid. https://quizlet.com/211198780/world-geography-a-unit-1-end-of-unit-test-flash-cards/