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
Monckeberg sclerosis involves which vessel layer 
Select and explain. 
A. Intima, B. Media, C. Externa, D. All of the above
B: Media
Answer: B: Media 
Explanation: Mockeberg sclerosis is calcification of Medial layer of arteries.
They are non obstructive and asymptomatic.