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: Gynaecology & Obstetrics
[{'content': 'Ligamentum teres is formed from : \nSelect and explain. \nA. Umbilical Aery, B. Umbilical Vein, C. Urachus, D. Persistent vitellointestinal duct', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Umbilical Vein', 'role': 'assistant'}]