Final answer:
The option that is not a taxonomic domain is B. Plantae. The three recognized domains are Bacteria, Archaea, and Eukarya, with the latter containing the kingdoms of plants, animals, fungi, and protists.
Step-by-step explanation:
The question asks which of the following is not a taxonomic domain of living things. The correct answer to this question is B. Plantae. Taxonomic domains are the highest level of organization in the biological classification system, and currently scientists recognize three domains: Bacteria, Archaea, and Eukarya. The domain Eukarya is characterized by cells with nuclei and includes kingdoms such as animals, plants, fungi, and protists. In contrast, both Bacteria and Archaea consist of unicellular prokaryotic organisms, which means their cells do not contain a nucleus. The domain Plantae is not at the same level as domains; it is one of the kingdoms within the Eukarya domain.
Domains are a relatively new concept in taxonomy, introduced in the late 20th century based on the pioneering work of Carl Woese and others who used ribosomal RNA to refine the phylogenetic tree of life. This new system organized all life into the three domains, supplanting the older five-kingdom division. The recognition of three separate domains significantly altered our understanding of life's evolutionary history.