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
[{'content': 'Monckeberg sclerosis involves which vessel layer \nSelect and explain. \nA. Intima, B. Media, C. Externa, D. All of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Mockeberg sclerosis is calcification of Medial layer of arteries.\nThey are non obstructive and asymptomatic.', 'role': 'assistant'}]