What type of organisms are placed in the domain Bacteria?

Correct answer: True prokaryotes (Eubacteria)

Direct answer: B, true prokaryotes called eubacteria. In the three-domain system, domain Bacteria contains the true bacteria, also called eubacteria. Their cells are prokaryotic: they lack a membrane-bound nucleus and do not possess membrane-bound organelles such as mitochondria. Many bacterial cell walls contain peptidoglycan, although the exact wall structure can vary among groups. A is wrong because eukaryotes belong to domain Eukarya and have a membrane-bound nucleus. C is wrong because Archaea are prokaryotes but are placed in their own domain, Archaea, due to important molecular and biochemical differences. D is wrong because viruses are acellular and are not placed in the three cellular domains. Memory cue: three domains are Bacteria, Archaea and Eukarya; the first contains true bacteria, the second contains archaea, and the third contains eukaryotes.