This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skeletal System, Subject name: Radiology
[{'content': 'Most common site of OPLL is? \nSelect and explain. \nA. Cervical spine, B. Thoracic spine, C. Lumbar spine, D. Sacrum', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans AOssified Posterior Longitudinal Ligament (OPLL) - is most commonly seen in mid cervical region where it classically causes spinal canal stenosis and cord compression.', 'role': 'assistant'}]