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: Unknown
[{'content': 'A coin is struck at 25 cm from incisor in the esophagus, this place coincides with - \nSelect and explain. \nA. Cricopharyngeal junction, B. Bronchus bifurfation, C. Aortic arch, D. Oesophago-gastric junction', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans-C Barium swallow may show a constriction at three site : QCricopharyngeal junction - Narrowest point (15 cm from incisor) QMiddle narrowing - crossing of the left main stem bronchus and aortic arch (25 cm from incisor). QLower most narrowing - At the hiatus of the diaphragm (40 cm from incisor)', 'role': 'assistant'}]