This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diagnosis of Pregnancy, Subject name: Gynaecology & Obstetrics
[{'content': 'Ideal time for doing quadruple test: \nSelect and explain. \nA. 8 - 12 weeks, B. 11- 15 weeks, C. 15 - 21 weeks, D. 20- 22 weeks', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Quadruple test : It includes alpha-fetoprotein (AFP) human chorionic gonadotropin (hCG) unconjugated estriol (uE3) inhibin A . Ideal time to do quadruple test is 15-21 weeks', 'role': 'assistant'}]