The correct option is D Phospholipids
Chemically, cell membrane or plasma membrane is composed of proteins, lipids, carbohydrates and water. Lipids are generally, phospholipids with polar hydrophilic head and non-polar hydrophobic tail. Thus, the structure of plasma membrane is called as phospholipid bilayer structure. Other lipids present in the cell membrane are cholesterol, cerebrosides, gangliosides and sphingomyelins. Thus, the correct answer is option D.