Answer:b. self-identity markers
Explanation:the plasma membrane of a cell encloses the protoplasm of the cell.it is a thin, phospholipid bilayer embedded with proteins.carbonhydrate is also found in the membrane.
Carbonhydrate in the cell membrane are found binding to lipids and proteins,forming glycolipids and glycoproteins respectively.these carbonhydrates are collectively called glycocalyx.
The carbonhydrate of the membrane are found sticking out of the surface of the membrane and facing the external environment of the cell.they are involved in cell identification as they enables cells to recognize one another.
It also helps cells to interact with one another.