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
Which of the following would distinguish hydrocephalus due to aqueductal stenosis when compared to that due to Dandy Walker malformation- 
Select and explain. 
A. Third ventricle size, B. Posterior fossa volume, C. Lateral ventricular size, D. Head circumference
B: Posterior fossa volume
Answer: B: Posterior fossa volume 
Explanation: To under stand this question you are required to know the basics of CSF production and drainage.