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
Alpha fetoprotein is decreased in : 
Select and explain. 
A. Anencephaly, B. Anterior abdominal wall defects, C. Renal anomalies, D. Down's syndrome
D: Down's syndrome
Answer: D: Down's syndrome 
Explanation: Down's syndrome