15. Which of the following statement about biological membranes is TRUE? (A) Plasma membranes are asymmetric. The outer leaflet is enriched in phosphatidylserine, whereas the inner leaflet is enriched in phosphatidylcholine. (B) Membrane asymmetry is maintained predominantly by scramblase. (C) Cerebrosides are mostly found in the inner leaflet of plasma membranes. (D) Membrane curvature is controlled by cytoskeleton reorganization, and does not affected by changes in lipid composition. (E) Phospholipids with unsaturated fatty acyl chains increase membrane fluidity.