Archaea can be found living in many extreme environments such as hot springs, deep sea vents, and very salty lakes. The picture below shows some varieties of Archaea. Archaea are simple forms of life without nuclei, and many types have been around since the very early stages of life on Earth. Which of these describes Archaea?

A: Multi-celled eukaryotes
B: Single-celled eukaryotes
C: Single-celled prokaryotes
D: Multi-celled prokaryotes