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
Which of the following is not done for antenatal diagnosis of Down's syndrome: 
Select and explain. 
A. Amniotic fluid volume estimation, B. Alpha-fetoprotein estimation, C. Cordocentesis, D. Chorionic villous biopsy
A: Amniotic fluid volume estimation
Answer: A: Amniotic fluid volume estimation 
Explanation: None