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': 'Not true regarding Dandy-Walker cyst: \nSelect and explain. \nA. Cerebellar vermis hypoplasia, B. Hydrocephalus, C. Arachnoid cysts, D. Posterior fossa cyst', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Characteristic Triad of Dandy Walker : * Hypoplasia of Vermis * Cephalad Rotation of Vermian remnant and Cystic Dilation of Fouh Ventricle extending posteriorly * Enlarged Post Fossa with Torcular Lambdoid inversion', 'role': 'assistant'}]