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
Not true regarding Dandy-Walker cyst: 
Select and explain. 
A. Cerebellar vermis hypoplasia, B. Hydrocephalus, C. Arachnoid cysts, D. Posterior fossa cyst
C: Arachnoid cysts
Answer: C: Arachnoid cysts 
Explanation: 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