This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Rheumatoid Arthritis, Subject name: Orthopaedics
[{'content': 'Most common part of spine affected by Rheumatoid arthritis is? \nSelect and explain. \nA. Lumbar spine, B. Thoracic spine, C. Cervical spine, D. Sacrum', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. (c) Cervical spineRef.'.MR Imaging of the Spine and Spinal Cord by DetlevUhlenbrock p-375, Orthopedic surgery essentials- Spine by Christopher M. Bono, Steven R. Garfin p-188", 'role': 'assistant'}]