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: Radiology
[{'content': 'Most serious complication of myelogram is \nSelect and explain. \nA. Allergy, B. Transient neurological deficit, C. Headache, D. Arachnoiditis', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. Arachnoiditis', 'role': 'assistant'}]