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
Chronic villous sampling is done at : 
Select and explain. 
A. 4-6 weeks, B. 7-8 weeks, C. 9-11 weeks, D. 12-13 weeks
C: 9-11 weeks
Answer: C: 9-11 weeks 
Explanation: 9-11 weeks