Question

the universe is: a single galaxy. a small part of the solar system. all existing matter, energy, and space including all of the planets, stars, galaxies, and all the contents of space, and everything that exists. a fictional concept with no basis in reality.

Explanation:

The universe encompasses all existing matter, energy, and space. It includes planets, stars, galaxies, and everything that exists. A single galaxy is just a part of the universe. The solar system is a small part within a galaxy, which is within the universe. And the universe is a real - world concept, not fictional.

Answer:

all existing matter, energy, and space including all of the planets, stars, galaxies, and all the contents of space, and everything that exists.