This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Aneurysms and Dissections, Subject name: Pathology
[{'content': 'Classification of aortic dissection depends upon- \nSelect and explain. \nA. Cause of dissection, B. Level of aorta affected, C. Percentage of aorta affected, D. None', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Level of aorta affected Classification of Aortic dissectiono The risk and nature of serious complications of dissection depend strongly on the level of aorta affected, with the most serious complications occuring from the aortic valve to the arch,o Thus aortic dissections are generally classified into two types -1. Proximal lesion (Type A)o More common and more dangerous.o Involve either the ascending portion only or both ascending and the descending portion of aorta.2. Distal lesion (Type B)o Involve only discending part distal to subclavian artery.", 'role': 'assistant'}]