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: Pharmacology
Etanercept used in rheumatoid arthritis act by the inhibition of : 
Select and explain. 
A. TNF alpha, B. TFG beta, C. IL–2, D. IL–6
A: TNF alpha
Answer: A: TNF alpha 
Explanation: None