Epithelial cells have multiple functions. They may have different structures on one of their surfaces compared to their opposite surface. What property of these cells allows them to undergo these various functions?

A) Epithelial cells are polar.
B) Epithelial cells have an apical membrane and a basolateral membrane.
C) Epithelial cells have different proteins in different parts of their cell membrane.
D) Only A and B are true.
E) A, B, and C are all true.