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: Medicine
[{'content': 'Mallory - Weiss tear occurs at \nSelect and explain. \nA. Root of aorta, B. Oesophago gastric junction, C. Middle cerebral artery, D. Vertebro basilar artery', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]