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
[{'content': 'Which pa of the spine is most commonly affected in Rheumatoid ahritis: \nSelect and explain. \nA. Cervical, B. Lumbar, C. Thoracic, D. Sacral', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 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.', 'role': 'assistant'}]