Answer: Cell membrane
Step-by-step explanation:
Eukaryotic cells contain membrane-bound organelles, for example, a nucleus. These types of cells can form plants, animals, insects or fungi. Prokaryotic cells do not contain membrane-bound organelles. Examples of these type of cells can be Bacteria.
So, cell nuclei is not a common feature because it is only fond in Eukaryotic cells. And also, there are other membrane-bound organelles besides the nucleus. Then, organelles and complex structures is not a common feature either.
The cell membrane is a biological semi-permeable membrane that surrounds the cell. Its protects it by allowing substances into the cell and keeping others out. It is found in both types of cells.