This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abnormalities of Head Size, Subject name: Pediatrics
Which of the following leads to 'communicating' hydrocephalus? 
Select and explain. 
A. Choroid plexus papilloma, B. Arnold Chiari malformation, C. Dandy walker malformation, D. Vein of Galen malformation
A: Choroid plexus papilloma
Answer: A: Choroid plexus papilloma 
Explanation: In Choroid plexus papilloma- 'communicating' hydrocephalus occurs due to increased production of CSF. Rest are causes of obstructive hydrocephalus- obstruction to flow of CSF