This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intra Uterine Growth Restriction, Intrapaum and Antepaum Fetal Surviellance, Subject name: Gynaecology & Obstetrics
Diagnosis of Down syndrome at 11 weeks is best assessed by: 
Select and explain. 
A. Ultrasonography, B. Aminocentesis, C. Chronic villous biopsy, D. Dopper Ultrasound
C: Chronic villous biopsy
Answer: C: Chronic villous biopsy 
Explanation: Confirmatory test for Down's syndrome: 1. First trimester- Chorionic villous sampling(10-13th week) 2. Second trimester - Amniocentesis(16-18th week)