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: Radiology
[{'content': 'Which one of the following is a recognized X-ray feature of rheumatoid arthritis? \nSelect and explain. \nA. Juxta-articular osteosclerosis, B. Sacroilitis, C. Bone erosions, D. Peri-articular calcification', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Radiological findings of RA:- Periarticular soft tissue swelling, periarticular osteopenia, Marginal erosion, subchondral cysts, widening of joint space (early), narrowing of joint space (later), ankylosis, subluxation or dislocation, and arthritis mutilans (late in the disease).', 'role': 'assistant'}]