Which of the following statements about membrane structure is true?
A. Cholesterol molecules extend across the lipid bilayer so that their charged ends can interact with water.
B. Glycolipids are only found on the cytoplasmic side.
C. Peripheral proteins are usually found only on the cell surface, not the cytoplasmic side of the membrane.
D. Lipids move readily within one side of the bilayer but rarely flip from one side to the other.