This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Normal Labour, Subject name: Gynaecology & Obstetrics
[{'content': 'AG2P1 to female has a history of previous preterm birth at 32 weeks. The percentage chances of preterm birth in this pregnancy are: \nSelect and explain. \nA. 5%, B. 10%, C. 15%, D. 25%', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. is c, i.e. 15%Ref. Williams Obs 24/e, p 841Recurrent spontaneous preterm births according to prior outcomeBirth outcomeSecond birth (<34 weeks) (%)First birth >=35 weeks5First birth <=34 weeks16First and second birth <=34 weeks41', 'role': 'assistant'}]