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: Surgery
[{'content': 'Double contrast phase contrast arthroscopy is used\nto study \nSelect and explain. \nA. Clicking of TMJ, B. Deviation of TMJ, C. Joint space, D. Disc', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]