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': 'Atonic post paum hemorrhage occurs in all except : \nSelect and explain. \nA. Multiple pregnancy, B. Hydramnios, C. Erythroblastosis fetalis, D. Prolonged labour', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Erythroblastosis fetalis', 'role': 'assistant'}]