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: Surgery
[{'content': '3rd constriction of the oesophagus is at the level of- \nSelect and explain. \nA. Left brunchus crossing the aorta, B. Where it pierces the diaphragm, C. Junction of the oesophagus and stomach, D. Cricopharynx', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]