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
Regarding Dandy-Walker syndrome, all are seen except- 
Select and explain. 
A. Hydrocephalus, B. Arachnoid cyst, C. Posterior fossa cyst, D. Cerebellar vermis deficiency
B: Arachnoid cyst
Answer: B: Arachnoid cyst 
Explanation: Dandy-walker malformation

The Dandy-Walker malformation consists of a cystic expansion of the 4th ventricle in the posterior fossa and midline cerebellar hypoplasia.
There is : -
Hydrocephalus (90% of cases)
Agenesis of the cerebellar vermis and corpus callosum.
The rapid increase in head size with prominent occiput.