14. The relative impermeability of membranes to water-soluble molecules is a result of the
a. Nonpolar nature of water molecules.
b. Presence of large proteins that extend through both sides of membranes.
c. Presence of inorganic salt crystals scattered through some membranes.
d. Presence of cellulose and chemicals such as cutin, lignin, pectin, and suberin in the membranes.
e. Presence of phospholipids in the lipid bilayer.