Answer:
Single celled organism
Explanation:
They fall under two categories:
Eukaryotes and prokaryotes.
Eukaryotes: Evolved from prokaryotes, they are larger and more complex. Unlike prokaryotes, they have a nucleus. Can be single celled or multicellular.
Prokaryotes: Oldest cell type, small and simple. They do not have a nucleus. Open unit with no compartments.
