Here's why:

* Single-celled organisms are complete living beings comprised of a single cell.

* Cell division is the process by which a single cell divides into two or more daughter cells.

* For single-celled organisms, this cell division is the primary way they reproduce, creating new individuals.

Examples of single-celled organisms that reproduce through cell division include:

* Bacteria

* Archaea

* Protozoa

* Some types of algae

* Yeast