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': 'Placenta previa mouth is associated with all of the following except: \nSelect and explain. \nA. Large placenta, B. Previous C. S. scar, C. Primigravida, D. Previous placenta previa', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Placenta previa is implantation of the placenta partially or completely over the lower uterine segment. Damage to the endometrium or myometrium due to previous surgery or infection can predispose to low implantation and placenta previa.\nRisk factors for placenta previa:\n\nPrior surgery\xa0(cesarean section / Myomectomy Hysterotomy)\nPrevious uterine curettage\nEndometritis\nIncreasing maternal age (>35 years)\nIncreasing parity\nPlacental size –increased (as in multiple pregnancy)\nPlacental abnormality –Succenturiate lobe\nSmoking (due to defective decidual vascularisation)\nElevated prenatal maternal serum alpha fetoprotein levels (unexplained)', 'role': 'assistant'}]