This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diagnosis in obstetrics, Subject name: Gynaecology & Obstetrics
[{'content': 'Transabdominal CVS can be done in: \nSelect and explain. \nA. 7-9 weeks, B. 11-13 weeks, C. 8-9 weeks, D. done before 10 weeks', 'role': 'user'}, {'content': 'Answer: B \nExplanation: chorionic villous sampling trancervical:done in 10-12 weeks transabdominal:10 weeks to term D.C.DUTTA&;S TEXTBOOK OF OBSTETRICS,Pg no:107,7th edition', 'role': 'assistant'}]