This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pathology
[{'content': 'Classification of aoic dissection depends upon \nSelect and explain. \nA. Cause of dissection, B. Level of aoa affected, C. Percentage of aoa affected, D. None', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Aoic dissection occurs when blood splays apa the laminarplanes of the media to form a blood-filled channel within theaoic wall.The clinical manifestations of dissection depend primarily on the poion of the aoa affected; the most serious complicationsoccur with dissections involving the proximalaoa and arch.Thus, aoic dissections generally are classified into two types-Proximal lesions: type A dissections, Distal lesions,type B dissectionsRobbins Basic pathology,9th edition,pg no.347', 'role': 'assistant'}]