Here's why:

* Thermophiles are a type of extremophile, meaning they thrive in extreme environments. In this case, thermophiles live in very hot environments (like hot springs and hydrothermal vents).

* Prokaryotes are single-celled organisms that lack a nucleus and other membrane-bound organelles. They include bacteria and archaea.

* Eukaryotes are organisms whose cells have a nucleus and other membrane-bound organelles. They include plants, animals, fungi, and protists.

While both bacteria and archaea can be thermophiles, the majority of known thermophiles are archaea.