This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
[{'content': 'True about umbilical cord ? \nSelect and explain. \nA. Cantains two umbilical veins, B. Cantains one umbilical aery, C. Right umbilical vein disappears, D. Length is 25-30 cm.', 'role': 'user'}, {'content': "Answer: C \nExplanation: Umbilical cordUmbilical cord develops from connecting stalk, which extends from the caudal end of the embryo to the chorion.Umbilical cord is covered by amniotic epithelium and contains a core of mesenchyme known as whaan's jelly.Contents of umbilical cord are : (i) Whaon's jelly, (ii) Two umbilical aeries, (iii) One (left) umbilical vein, (iv)Remnant of yolk sac, and (v) Remnant of allanto-enteric diveiculum.Initially 2 umbilical aeries and 2 umbilical veins develop in mesoderm, but right umbilical vein disappears. Left umbilical vein persists along with 2 umbilical aeries.At full term, the umbilical cord measures 1-2cm in diameter, and 50-55cm in length and generally attached to the center of fetal surface of placenta.", 'role': 'assistant'}]