Which planets are the OUTER planets? Where did they form in the nebula disk? Why did they form where they did? (discuss temperature and density differences of the nebula disk)

The outer planets are Jupiter, Saturn, Uranus, and Neptune. Each planet began as microscopic dust and held in the accretion disk. The atoms and molecules began to stick together and formed into larger molecules. And the last one I dont know

It would have to be c or d