Which statement describes the phospholipid bilayer that makes up a cell membrane? a: the hydrophobic heads point into and out of the cell, while the hydrophilic tails form a layer between the heads. b: the hydrophobic tails point into and out of the cell, while the hydrophilic heads form a layer between the tails. c: the hydrophilic heads point into and out of the cell, while the hydrophobic tails form a layer between the heads. d: the hydrophilic tails point into and out of the cell, while the hydrophobic heads form a layer between the tails.