Analyze how chorionic villi facilitate the exchange of nutrients and gases between mother and fetus.

• A. They protect the fetus from maternal infections.
• B. They form the amniotic cavity around the fetus.
• C. They produce hormones essential for fetal development.
• D. They connect to the umbilical arteries and veins, allowing for direct exchange of nutrients, gases, and waste.

Answer: (D)