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: Pathology
Which one of the following is not a characteristic feature of rheumatoid arthritis ? 
Select and explain. 
A. Sacroiliitis, B. Metacarpophalangeal joint involvement, C. Symmetrical arthritis, D. Positive rheumatoid factor
A: Sacroiliitis
Answer: A: Sacroiliitis 
Explanation: None