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
The ___________ is the innermost meningeal layer, clings tightly to the surface of the brain and spinal cord, following every fold. 
Select and explain. 
A. Arachnoid mater, B. Pia mater, C. Dura mater, D. Tentorium cerebelli
B: Pia mater
Answer: B: Pia mater 
Explanation: B: The innermost layer that contours closely to the many folds and crevices of the brain is called the pia mater.
A: The arachnoid or arachnoid mater is the middle layer of the meninges.
C: Dura mater is the outermost layer of the meninges.
D: Tentorium cerebelli is an extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes.