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': 'Most characteristic anomaly in infant of a diabetic mother: \nSelect and explain. \nA. Caudal regression, B. VSD, C. Spina bifida, D. Anencephaly', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Caudal regression', 'role': 'assistant'}]