Answer
b. microvilli
Work Step by Step
Atop each brush border cell sit about 1,700 hairlike projections called microvilli. Each microvillus increases the surface area of the brush border cell on which it sits. These filaments have digestive enzymes at their surfaces that break down polypeptides, sugars, and nucleotides; they also contain transport proteins that move the products of digestion into the microvilli.
