Which term best describes organisms that can be unicellular or multicellular yet have a nucleus?

• A. Prokaryote
• B. Virus
• C. Bacterium
• D. Eukaryote

Answer: (C)

Having a nucleus and the potential to be either single-celled or many-celled describes organisms called eukaryotes. Eukaryotes have a true nucleus enclosed by a membrane and contain membrane-bound organelles, which supports complex organization. This group includes single-celled examples like yeast and multicellular ones like plants and animals. In contrast, prokaryotes such as bacteria lack a nucleus, so they don’t fit the description of organisms that both have a nucleus and can be unicellular or multicellular. Viruses aren’t cells and don’t carry out metabolism on their own, so they aren’t considered organisms in the same sense. So the term that fits the description is eukaryote.