Answer: C). cell membrane
The cell membrane is the membrane that can be found in both eukaryotic and prokaryotic cells. It is the cell that separates the interior of the cell from the extracellular environment. It is a protective layer that allows only the selected ions and organic molecules to enter inside the cells and go out of the cell, hence is called as selectively permeable or semi-permeable membrane. This phenomena maintains the concentration of ions and molecules inside the cell and prevents dehydration, cell rupture due to high concentration.
