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: Medicine
[{'content': "Alpha-fetoprotein in maternal serum and/or amniotic fluid is increased in all except - \nSelect and explain. \nA. Fetal neural tube defects, B. Down's syndrome, C. Anencephaly, D. Encephalocele", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]