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: Orthopaedics
All are increased in rheumatoid arthritis, except 
Select and explain. 
A. ESR levels, B. Rheumatoid factor, C. Anti-CCP Antibodies, D. Synovial fluid viscosity
D: Synovial fluid viscosity
Answer: D: Synovial fluid viscosity 
Explanation: None