This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'Urachus fistula is a remanant of ? \nSelect and explain. \nA. Yolk sac, B. Allantois, C. Chorion, D. Amnion', 'role': 'user'}, {'content': "Answer: B \nExplanation: Urachus fistula is a remnant of allantoic diveiculum If patent urachus in adults, urine dribbles from umbilicus known as wheeping umbilicus Inderbir Singh's Human embryology Pg 97", 'role': 'assistant'}]