Which of the following best describes the relationship between the structure of the cell membrane and its function? a) the cell membrane folds upon itself easily, which facilitates cellular reproduction by mitosis. b) the membrane is rigid and inflexible, preventing the movement of substances across the cell membrane. c) the outer layer of the membrane is hydrophilic, which allows water to flow in and out of the cell easily to eliminate waste. d) the proteins that are embedded in the cell membrane act as channels to transport substances in and out of the cell