A student studies Earth and learns that it has several layers, including inner and outer cores. The student will make a model of the inner and outer cores of Earth. Which model would be most like Earth's actual inner and outer cores

A. a pool of liquid inside a solid metal ball

B. a solid metal ball with a slightly smaller solid metal ball inside it

C. a solid metal ball in the middle of a pool of liquid

D. a pool of one type of liquid in the middle of a pool of another type of liquid