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
Which of the following is the most specific test for Rheumatoid ahritis 
Select and explain. 
A. Anti-ccp antibody, B. Anti Igm antibody, C. Anti IgA antibody, D. Anti IgG antibody
A: Anti-ccp antibody
Answer: A: Anti-ccp antibody 
Explanation: to establish diagnosis of rheumatoid ahritis are * Clinical criteria * ESR and CRP * Ultrasound or MRI * Rheumatoid factor and anti-citrullinated peptide antibodies DAVIDSON&;S 22nd EDITION;PAGE NO 1100