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': 'Berry aneurysm - defect lies in - \nSelect and explain. \nA. Degeneration of internal elastic lamina, B. Degeneration of media/muscle cell layer, C. Deposition of mucoid material in media, D. Low grade inflammation of vessel wall', 'role': 'user'}, {'content': "Answer: B \nExplanation: Berry's aneurysm is a brain aneurysm caused due to a defect in media. Berry aneurysms arise at the point of weakness in the arterial media, especially branch points in the circle of Willis.\nThere is a congenital defect in tunica media of cerebral vessels which leads to aneurysm formation.", 'role': 'assistant'}]