Answer:
Archaebacteria
Explanation:
Archaebacteria is one of the three domains in which living organisms are classified into. These set of organisms are characterized by their prokaryotic nature i.e lack of membrane-bound nucleus and their unique ability to withstand extreme environmental conditions e.g heat etc.
Based on the explanation above, the organism described in this question as being discovered by scientists and have the ability to thrive in hot water that is 90*C (194°F) and do not need sunlight or oxygen (anaerobic) to live is likely to belong to the kingdom ARCHAEBACTERIA.
