Concept:Villi are tiny projections inside the small intestine that help in digestion by absorption.
Explanation:The villi greatly increase the internal surface area of the intestinal wall.
A larger surface area allows digested nutrients to be absorbed into the bloodstream quickly.
Villi never secrete gastric juice, as that is the work of stomach glands.
Villi do not curdle milk; that is performed by enzymes in the stomach.
Emulsification of fat is done by bile, not by villi.
Thus, the only correct role of villi is to provide an expanded surface for efficient absorption.
Answer:D. increase the surface area for absorption