Answer: The correct answer is-
A) Archaea.
Archaea is considered as one of the three domains of life forms according to the three domain classification system of Carl Woese.
It consists of the most primitive forms of bacteria (prokaryotes) that survive under extremely harsh environmental conditions (therefore also termed extremophiles) such as hotsprings, hydrothermal vents, extreme acidic and salty conditions etc.
Example of Archaea- Methanogens.