Computer Simulations of the Formation of the Solar System Show

Computer simulations of the formation of the solar system show that the material in the vicinity of the asteroid belt is NOT in the form of one large planet because

A) most of the material originally in the asteroid belt crashed into Mars, creating the heavily cratered terrain seen there.
B) a violent collision destroyed two protoplanets, the debris from which became the asteroid belt.
C) this region is where the gravitational field of the Sun is exactly balanced by that of Jupiter.
D) Jupiter's gravitational pull prevented them from coalescing into a planet.