Correct Answer - B
The lipid molecules are amphipathic, i.e., they posses both polar hydrophilic (water loving) and nonpolar hydrophobic (water repelling) ends. The hydrophilic region is in the form of a head occurring at outer surface while the hydrophobic part contains two tails of fatty acids. Hydrophobic tails usually occur towards the centre of the membrane. It in the formation of a lipid bilayer. Most common lipid in the bilayer is phospholipid.