Archaea are typically found living in extreme environments. an exception to this are the a. sulfur-oxidizing archaea. b. sulfur-reducing archaea. c. methanogens. d. sulfur-oxidizing archaea and sulfur-reducing archaea.

C - Methanogens

Explanation:

As their name says, methanogens are organisms that produce methane, turning CO₂ and H₂ into methane and water as a way of obtaining energy.

While some methanogens are found in extreme environments, the most common place where you can find them is inside the human body, as a part of the human microbiota.

The human microbiota is the set of all living organisms that live inside the human body, helping it in different ways. Methanogens, in particular, are present in the gut and produce the methane expulsed in flatulences, being an important part of the process of digestion by reducing H₂ levels.