Answer:
A
Explanation:
Archaebacteria, meaning “old bacteria,” are grouped like that because of DNA differences and because they live in extreme environments, like salty, very hot, or very cold.
Eubacteria, meaning “true bacteria,” are grouped separately from archaebacteria because they do not exhibit those traits. Living in extreme environments is a characteristic of archaea.
Why not B: this describes archaebacteria.
Why not C: bacteria are unicellular, though they can aggregate into groups.
Why not D: they can be anaerobic or aerobic (use oxygen).
