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: Surgery
[{'content': 'A new born presents with mid anterior abdominal wall defect with characteristic spontaneous disappearance at age of 4 years - \nSelect and explain. \nA. Patent urachus, B. Omphalocele, C. Ectopia vesicae, D. Umibilical hernia', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]