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': "Alpha fetoprotein is decreased in : \nSelect and explain. \nA. Anencephaly, B. Anterior abdominal wall defects, C. Renal anomalies, D. Down's syndrome", 'role': 'user'}, {'content': "Answer: D \nExplanation: Down's syndrome", 'role': 'assistant'}]