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
Alpha-fetoprotein in maternal serum and/or amniotic fluid is increased in all except - 
Select and explain. 
A. Fetal neural tube defects, B. Down's syndrome, C. Anencephaly, D. Encephalocele
B: Down's syndrome
Answer: B: Down's syndrome 
Explanation: None