The Absorptive Epithelial Cells Lining the Inner Wall of the Alimentary

The absorptive epithelial cells lining the inner wall of the alimentary canal (digestive tract) are considered "polarized" because

A) they pump wastes into the lumen while pumping nutrients toward the blood.
B) the colors seen on the top and bottom of the cells are different.
C) they must initiate action potentials to absorb most nutrients.
D) the structures on the apical surface are different from those on the basal surface.