Suppose We Had a Device That Allowed Us to See

Suppose we had a device that allowed us to see Earth's interior. If we looked at a typical region of the mantle, what would we see happening?

A) Not much-on human time scales, the mantle looks like solid rock.
B) dense metals falling downward while low- density rock rises upward
C) a rapid, up and down churning of the material in the mantle
D) hot molten rock rising upward throughout the mantle and cool, solid rock falling downward