What feature distinguishes eukaryotes from prokaryotes?

The presence of a nucleus is a defining characteristic that distinguishes eukaryotes from prokaryotes. Eukaryotic cells contain a true nucleus, which is surrounded by a nuclear membrane and houses the cell's genetic material (DNA) organized into chromatin. This compartmentalization allows for more complex regulation of gene expression and a greater degree of cellular organization. In contrast, prokaryotic cells do not have a membrane-bound nucleus; instead, their genetic material is located in a region called the nucleoid, which is not enclosed by a membrane. This fundamental difference in cellular organization reflects the complexity of eukaryotic organisms, which can be unicellular or multicellular, compared to prokaryotic organisms, which are predominantly unicellular.

The other features listed—ribosomes, membrane-bound organelles, and cell wall composition—are either present in both groups or do not distinctly separate eukaryotes from prokaryotes. For instance, ribosomes are found in both eukaryotic and prokaryotic cells, although they differ in size and structure. Additionally, while eukaryotes have membrane-bound organelles, prokaryotes have simpler cellular structures without these compartments. Lastly, cell wall composition varies