27. Lung surfactants function to decrease the likelihood of collapse of the alveoli when air is expired. Based on your knowledge of lipids and amphipathic molecules, which of the following explains the mechanism by which the dipalmitoyI phosphatidylcholine (DPPC) can accomplish this task? (A) The choline portion of the molecule is bulky, thus increasing surface area of alveoli. (B) 'The inclusion of saturated fatty acids on the glycerophospholipid allows close packing of tail groups which are fully extended and prevent collapse upon expiration. (C) The hydrophilic head groups are bulky and expand the surface area of the alveoli. (D) The hydrophobic portion of the DPPC repel air, foreing the alveoli space open