The nurse is reviewing fetal and maternal circulation with a group of nursing students. Which statement by a student demonstrates a need for further clarification?

A. "The placenta is the site of gas exchange for the fetus." This is correct because the placenta facilitates oxygen and carbon dioxide exchange between maternal and fetal circulation without direct blood mixing. B. "The umbilical arteries carry deoxygenated blood from the fetus to the placenta." This is correct because the two umbilical arteries carry deoxygenated blood from the fetus to the placenta, where gas exchange occurs. C. "The fetal heart pumps blood to both the placenta and the developing organs." This is correct because the fetal heart pumps oxygenated blood to its developing organs and sends deoxygenated blood to the placenta for gas exchange. D. "Maternal and fetal blood mix to allow for nutrient and oxygen exchange." This is incorrect because maternal and fetal blood do not mix under normal conditions. Instead, nutrients, gases, and waste products pass through the placental barrier via diffusion. If maternal and fetal blood mix, it could indicate a placental rupture or pathological condition.