Which group contains organisms that inhabit extreme environments?

The correct answer is Archaea because this group is known for comprising organisms that thrive in extreme environments, such as hot springs, salt lakes, and deep-sea hydrothermal vents. Archaea possess unique biochemical and genetic characteristics that enable them to survive and even flourish under conditions that would be inhospitable to most other life forms. For instance, many archaea have specialized cell membranes and metabolic pathways that allow them to withstand high temperatures, high salinity, or low pH levels.

In contrast, while Bacteria also include some extremophiles, they are generally more diverse and encompass a broader range of environments, including those that are not extreme. Eukarya is the domain that includes more complex organisms, such as plants, animals, and fungi, which typically inhabit more moderate environments. Protists, a sub-group within Eukarya, also tend to prefer well-defined ecological niches rather than extreme habitats. Thus, Archaea stands out as the group specifically adapted to extreme environments.