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: Surgery
Which pa of the spine is most commonly affected in Rheumatoid ahritis: 
Select and explain. 
A. Cervical, B. Lumbar, C. Thoracic, D. Sacral
A: Cervical
Answer: A: Cervical 
Explanation: Answer is A (Cervical): Rheumatoid ahritis commonly involves the joints of hands, wrist, elbow, knees, ankle, and feet in a symmetrical manner. Axial skeleton involvement is usually limited to Upper Cervical Spine.