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
Obstruction to the flow of CSF at the aqueduct of sylvius will most likely lead to enlargement of ? 
Select and explain. 
A. All of the ventricles, B. Only lateral ventricle, C. Only fouh ventricle, D. Both lateral and third ventricles
D: Both lateral and third ventricles
Answer: D: Both lateral and third ventricles 
Explanation: Ans. is `d' i.e., Both lateral and third ventricle o CSF is produced by choroid plexus in the lateral and III ventricles. Then it flows through the aqueduct ofsylvius into the 4th ventricle and from there into the subarachnoid space to be absorbed by the arachnoid villi. o Obviously any obstruction in the aqueduct of sylvius will lead to enlargement of the proximal ventricles (i.e. both lateral and HP' ventricles).