Why are humans not able to digest cellulose?
a. humans lack the enzyme cellulase, which is required to hydrolyze the β(1→4) glycosidic bonds present in cellulose.
b. humans lack the enzyme lactase, which is required to hydrolyze the lactose produced from the digestion of cellulose into glucose and galactose.
c. humans lack the enzyme lactase, which is required to convert the galactose produced from the digestion of cellulose into glucose.
d. cellulose is not naturally available to humans.
e. none of the above; humans actually can readily digest cellulose?