According to Our Present Theory of Solar System Formation, Which

Multiple Choice

According to our present theory of solar system formation, which of the following best explains why the solar nebula ended up with a disk shape as it collapsed?

A) The force of gravity pulled the material downward into a flat disk.
B) It was fairly flat to begin with, and retained this flat shape as it collapsed.
C) The law of conservation of energy
D) It flattened as a natural consequence of collisions between particles in the nebula.