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': "Bandl's ring is also called as: \nSelect and explain. \nA. Constriction ring, B. Schroeder's ring, C. Retraction ring, D. Cervical dystocia", 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]