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': 'The most impoant single special investigation in lumbar disc prolapse is \nSelect and explain. \nA. Epidurography, B. Myelography, C. MRI, D. Discography', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. MRI', 'role': 'assistant'}]