Humans can digest starch but not cellulose because

A) the monomer of starch is glucose, while the monomer of cellulose is galactose.
B) humans have enzymes that can hydrolyze the β glycosidic linkages of starch but not the α glycosidic linkages of cellulose.
C) humans have enzymes that can hydrolyze the α glycosidic linkages of starch but not the β glycosidic linkages of cellulose.
D) humans harbor starch-digesting bacteria in the digestive tract.
E) the monomer of starch is glucose, while the monomer of cellulose is glucose with a nitrogen-containing group.