Answer the following question given this paragraph: 

Some comets have periods of thousands or even millions of years. Most long-period comets come from a very distant region of the solar system. This region is called the Oort cloud. The Oort cloud is about 50,000–100,000 times the distance from the Sun to Earth.


Q: What is the name of the cloud where most long-period comets come from?

 Choices:

- stellar cloud

- bulge cloud

- volt cloud

- oort cloud

A:
oort cloud
