Answer:
The most appropriates answer would be C) They are both composed of prokaryotic organisms. The Archaea live in very extreme environments, like hot springs, but the Bacteria do not.
Archaea are prokaryotic unicellular organisms that is, they lack well defined nucleus. However, they have distinct chemical or molecular characteristics which differ them from the bacteria.
These organisms were originally discovered in extreme conditions such as hydrothermal vents. They can survive in diverse range of high acidic, saline, and anaerobic environment. They are also termed as extremophiles.
On other hand, bacteria are also prokaryotic unicellular organisms. They can inhabit in any area including air, water, soil, decaying organism et cetera however, they are usually not found in such extreme conditions in which archaea can survive.
For example, <em>Pyrolobus fumarii</em> can survive even at 113 °C temperature.