The answer would be B. Atom, star, galaxy, universe.
Explanation: atoms are small cells that make up everything in existence. They're too small to be seen by the naked human eye. Stars are big balls of gas that can be seen at night in the sky. These are second biggest because you can see these with the naked eye, but galaxies you can not. The galaxy holds the earth, all of the other planets, stars, and other things. If the galaxy can hold all of that then clearly it would be bigger than the stars. The universe is what holds our galaxy. There are millions of other galaxies out there in the universe. Ours is just a small one of an infinite number.
