● The correct option is (3) because lipids having only single bonds are called saturated fatty acids and lipids having one or more C = C double bonds are called unsaturated fatty acids. ● Palmitic acid has 16 carbon atoms including carboxyl carbon. ● Arachidonic acid has 20 carbon atoms including the carboxyl carbon. ● Lecithin is a phospholipid found in cell membrane. ● Glycerol has 3 carbons, each bearing a hydroxyl (–OH) group.