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
Meningomyelocele patient after being operated developed hydrocephalus due to: 
Select and explain. 
A. Arnold Chiari malformation, B. Injury to absorptive surface, C. Central canal injury, D. Arachnoidal block
A: Arnold Chiari malformation
Answer: A: Arnold Chiari malformation 
Explanation: Type II Chiari malformation is characterized by progressive hydrocephalus with a myelomeningocele.