What is a possible icy cloud surrounding the solar system from which some comets originate?

There are 2 regions that are considered as the place where comets originated, these are the Kuiper Belt and Oort Cloud. There are 2 types of comets that travel in our solar system, the short period and has a short orbit (few hundred years) is come from the region of Kuiper Belt and the longer period comets and longer orbit (thousands of years) come from Oort Cloud. But this 2 differs in the distance and location. The Kuiper Belt orbits are near with the pluto's orbit. Meaning it has an orbit which is approximately the same as the planets. The Oort Cloud region is the possible icy cloud that refers above. It is a shell which surrounds the solar system. 

Ithink the best answer is d increased stability of all other biomes