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: Medicine
Etanercept used in rheumatoid arthritis act by - 
Select and explain. 
A. TNF alpha, B. TFG beta, C. IL-2, D. IL-6
A: TNF alpha
Answer: A: TNF alpha 
Explanation: None