This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fetus Placenta & Fetal Membrane, Subject name: Gynaecology & Obstetrics
[{'content': 'Ligamentum teres is formed after: \nSelect and explain. \nA. Obliteration of the umbilical vein, B. Obliteration of the ductus venous, C. Obliteration of the ductus arteriosus, D. Obliteration of the hypogastric artery', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. is a, i.e. Obliteration of the umbilical veinVesselRemnantUmbilical arteryMedial umbilical ligamentLeft umbilical veinLigamentum teres of the liver', 'role': 'assistant'}]