Which structure is unique to eukaryotic cells? DNA cell membrane ribosomes nucleus

The structure that is unique to eukaryotic cells is the nucleus. Eukaryotic cells have a true nucleus enclosed by a nuclear membrane, which contains the cell's genetic material (DNA). In contrast, prokaryotic cells (such as bacteria) do not have a true nucleus; their DNA is located in a region called the nucleoid. The other structures listed (DNA, cell membrane, and ribosomes) are found in both eukaryotic and prokaryotic cells.