This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Joint disorders, Subject name: Orthopaedics
[{'content': 'Earliest radiological change in RHEUMATOID AHRITIS is ? \nSelect and explain. \nA. Decreased joint space, B. Aicular erosion, C. Periaicular osteopenia, D. Subchondral cyst', 'role': 'user'}, {'content': 'Answer: C \nExplanation: REF : MAHESWARI 9TH ED', 'role': 'assistant'}]