Answer:A). Phospholipids
Explanation: A cell membrane is a phospholipid bilayer. Phospholipids have two components: the fatty acid chain and the phosphate head group. The phosphate groups of the phospholipids are polar while the fatty acyl chains are nonpolar. The nonpolar fatty acyl chains face each other forming a bilayer while the phosphate head group face outward interacting with the environment. The cell membrane contains other components such as the proteins and carbohydrate chains but in lesser amount, therefore the major constituent of the cell membrane is phospholipids.