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
Abatacept, a new drug inhibiting co-stimulation is used for- 
Select and explain. 
A. SLE, B. Scleroderma, C. Rheumatoid ahritis, D. Sjogren syndrome
C: Rheumatoid ahritis
Answer: C: Rheumatoid ahritis 
Explanation: Ref Davidsons 23e p1007