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: Anatomy
Function of CSF can be: 
Select and explain. 
A. Protective., B. Nutritive., C. Pathway for excretion from the CNS., D. All of the above.
D: All of the above.
Answer: D: All of the above. 
Explanation: None