This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
The detection rate of Down syndrome with first-trimester screening with NT, PAPP-A, and hCG is 
Select and explain. 
A. 64-70%, B. 80-84%, C. 94-96%, D. 99%
B: 80-84%
Answer: B: 80-84% 
Explanation: Selected Down Syndrome Screening Strategies and Their Detection Rate: Screening test Detection rate Quadruple screen 80-82% First-trimester screen NT alone 64-70% NT, hCG, PAPP-A 80-84% Integrated screening 94-96% Sequential screening Stepwise 92% Contingent 91% Cell-free DNA 91%