Answer:b. Certain proteins are unique to each membrane.
Explanation:
Cell membranes of the eukaryotes are composed of proteins and lipids. The membranes of the eukaryotic cells are composed of lipid bilayers associated with the proteins. The proteins may differ in composition depending upon the type of cell. The membrane proteins act like a signal sequences to target other proteins to respective destinations to perform desired functions. Therefore, option B is correct.