This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immune system, Subject name: Medicine
[{'content': 'Abatacept, a new drug inhibiting co-stimulation is used for- \nSelect and explain. \nA. SLE, B. Scleroderma, C. Rheumatoid ahritis, D. Sjogren syndrome', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ref Davidsons 23e p1007', 'role': 'assistant'}]