Why Can Asteroids Not Stick Together and Form a Planet

Multiple Choice

Why can asteroids not stick together and form a planet?

A) They are traveling too fast,so there are no collisions.
B) They are travelling so fast that individual collisions are too energetic to allow the asteroids to unite.
C) The gravitational acceleration caused by Jupiter causes asteroids to move away from each other.
D) They are more likely to collide with Jupiter because of the strong gravitational pull.
E) None of these choices are correct.