Correct Response: A. In the five-kingdom taxonomic scheme, all prokaryotes were classified in a single kingdom called Monera. In the three-domain system, prokaryotes fall into separate domains (Bacteria and Archaea), and all eukaryotic organisms fall into the Eukarya domain. Protista are eukaryotes; as such they remain in a domain distinct from all prokaryotes (B). Autotrophs can be found in the Monera, Protista, and Plantae kingdoms in the five-kingdom scheme, so the shift did not separate a single autotroph kingdom into different domains (C). Unicellular organisms can be found in each of the three domains in the domain scheme, so the grouping of all unicellular organisms into one domain was not accomplished by the shift to the three-domain scheme (D).
