This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cerebrovascular Diseases, Subject name: Surgery
[{'content': 'Meningomyelocele patient after being operated developed hydrocephalus due to: \nSelect and explain. \nA. Arnold Chiari malformation, B. Injury to absorptive surface, C. Central canal injury, D. Arachnoidal block', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Type II Chiari malformation is characterized by progressive hydrocephalus with a myelomeningocele.', 'role': 'assistant'}]