Final answer:
Villi, microvilli, and plicae circulares are structural characteristics of the small intestine that enhance absorption of macronutrients. 4) Goblet cells, on the other hand, do not enhance absorption.
Step-by-step explanation:
The structural characteristics of the small intestine that enhance absorption of macronutrients include villi, microvilli, and plicae circulares. These features increase the surface area available for nutrient absorption. However, goblet cells are not a structural characteristic that enhances absorption, as they produce mucus to lubricate the intestine.