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: Unknown
[{'content': 'A multiparous woman delivered by a village dai (midwife) presents on the 22nd postnatal day with bleeding per vaginam with clost. On examination, the uterus is 14-16 weeks, the internal os is open, and there is bleeding through the os. The likely cause of this bleeding is - \nSelect and explain. \nA. Excessive postnatal physical work, B. Perineal tears, C. Retained bits of placenta and membranes, D. None of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans-C', 'role': 'assistant'}]