This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Rheumatoid Ahritis, Subject name: Medicine
[{'content': 'The most specific antibody for Rheumatoid ahritis is? \nSelect and explain. \nA. Antinuclear antibody (ANA), B. Rheumatoid factor, C. Anti-cyclic citrullinated peptide (anti-CCP) antibody, D. Anti-double stranded DNA antibody', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Anti-CCP is the most specific antibody for rheumatoid ahritis with specificity of 95%. 20% patients have elevated ANA and ESR. CRP levels are elevated propoional to disease activity.', 'role': 'assistant'}]