Concept:The villi are tiny, finger-like projections lining the inner wall of the small intestine.Explanation:They greatly increase the internal surface area of the alimentary canal.This larger surface area makes the absorption of digested food into the bloodstream faster and more efficient.Villi do not secrete gastric juice, curdle milk, or emulsify fat; those are functions of other digestive structures and secretions.Answer:D. increase the surface area for absorption