Answer:
D.It got hotter, its rate of rotation increased, and it flattened into a disk
Explanation:
The nebula theory proposes that our solar system was born about 4.6billion years ago out of a gigantic interstellar cloud.
These interstellar gases are made up of some gases and some microscopic particles. The gravitational pull by the particles caused the cloud to collapse inward. The collapse triggered increase in temperature and the rate of rotation spiked. This caused the collapsed cloud to flatten into a disk with a centre bulge which later forms the sun.