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
[{'content': 'The best period of gestation to carry out chorion villous biopsy for prenatal diagnosis is? \nSelect and explain. \nA. 8-10 weeks, B. 10-12 weeks, C. 12-14 weeks, D. 14-16 weeks', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Chorionic villus sampling (CVS) is carried out transcervical between 10-12 weeks and trans-abdominal from 10 weeks to term. Ref:Textbook of Gynecology By D C Dutta, 5th Edition, Page 315', 'role': 'assistant'}]