Why does the author provide the information that "It is much easier for an icy body to differentiate than for a rocky one"? A. To support the claim that all of the big icy moons are differentiated B. To suggest that Callisto may be a rocky body rather than an icy one C. To explain why scientists expected Callisto to be differentiated D. To refute the claim that Callisto could not differentiate because it was frozen solid