This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: AIIMS 2018, Subject name: Pathology
Which of the following is not a pa of the quadruple test for antenatal detection of Down syndrome? 
Select and explain. 
A. AFP, B. Estriol, C. Beta HCG, D. Inhibin B
D: Inhibin B
Answer: D: Inhibin B 
Explanation: TRIPLE TEST b Hcg || a feto protein || Estriol || QUADRAPLE TEST BHcg || A feto protein || Estriol || Inhibin A ||