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: Pathology
[{'content': 'Regarding Dandy-Walker syndrome, all are seen except- \nSelect and explain. \nA. Hydrocephalus, B. Arachnoid cyst, C. Posterior fossa cyst, D. Cerebellar vermis deficiency', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Dandy-walker malformation\n\nThe Dandy-Walker malformation consists of a cystic expansion of the 4th ventricle in the posterior fossa and midline cerebellar hypoplasia.\nThere is : -\nHydrocephalus (90% of cases)\nAgenesis of the cerebellar vermis and corpus callosum.\nThe rapid increase in head size with prominent occiput.', 'role': 'assistant'}]