This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Anatomy
[{'content': 'Most common cause of postpaum hemorrhage is: \nSelect and explain. \nA. Uterine atony, B. Retained products, C. Trauma, D. Bleeding disorders', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Most common cause of primary postpaum hemorrhage is Atonic uterus Most common cause of secondary postpaum hemorrhage is Retained placenta Ref: Datta Obs 9e pg 393.', 'role': 'assistant'}]