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': 'A patient had undergo suction evacuation for 10 weeks pregnancy. Three days later she came back with profuse vaginal bleeding and abdominal pain. The most likely diagnosis is : \nSelect and explain. \nA. Uterine atony, B. Cervical injury, C. Retained products, D. Uterine perforation', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Retained products', 'role': 'assistant'}]