Concept:Villi are small finger-like projections found in the inner wall of the small intestine.
Their main role is to increase the surface area for absorbing digested food.
Explanation:After digestion, nutrients must pass from the intestine into the blood.
Villi provide a large surface area for this absorption.
They also contain blood vessels that carry absorbed nutrients away.
Starch digestion mainly occurs by enzymes, not by villi.
Water and some salts are absorbed mainly in the large intestine.
Transport of undigested food to the large intestine is done by peristalsis.
Thus, the correct function of villi is to increase the surface area for absorption of digested food.
Answer:Option D: increase the surface area for absorption of digested food.