This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fetal circulation, Subject name: Pediatrics
Maximum oxygen saturation is there in which of the following blood vessels in a fetus? 
Select and explain. 
A. Ascending aoa, B. Descending aoa, C. Inferior vena cava, D. Ductus venosus
D: Ductus venosus
Answer: D: Ductus venosus 
Explanation: Oxygen saturation of different blood vessels in fetus: Umbilical vein > Ductus venosus > Inferior vena cava > Ascending aoa > Descending Aoa > Umbilical aeries