This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Joint disorders, Subject name: Orthopaedics
In a case of undifferentiated ahritis, presence of anti-cyclic citrullinated peptide {anti CCP} indicates strong possibility of which of the following? 
Select and explain. 
A. Rheumatoid ahritis, B. Systemic lupus erythematosis, C. Mixed connective tissue disorder, D. Reactive ahritis
A: Rheumatoid ahritis
Answer: A: Rheumatoid ahritis 
Explanation: REF : MAHESWARI 9TH ED