The Oort Cloud is a distant region of the Solar System with billions of comets.
Why it is true
The Oort Cloud is a spherical shell of icy bodies believed to exist at the edges of the Solar System, up to 100,000 astronomical units from the Sun. It is the source of many long-period comets. It has never been observed directly.
Source: NASA
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.