Answer: Option A."Protein"
Explanation:
The plasma membrane, also known as cell membrane, is the membrane that separates the interior parts of the cell from the outside environment.
Proteins are one of the major chemical component of the plasma membranes. Integral proteins are embedded in the plasma membrane and serve as pumps or channels that allows the movement of materials in and out of the cell. Peripheral proteins are found on the exterior or interior surfaces of membranes, that forms structural attachments for the fibers of the cytoskeleton.
Hence, the correct option is A.
