This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Esophagus, Subject name: Surgery
[{'content': 'A coin foreign body is stuck in esophagus at 25cm from incisors. This is approximately situated at which of the following levels? \nSelect and explain. \nA. Left mainstem bronchus, B. Diaphragm, C. Cricopharyngeal constriction, D. Gastroesophageal junction', 'role': 'user'}, {'content': "Answer: A \nExplanation: On endoscopy, 3 narrowing's are seen from upper incisors. Mnemonic B - 15 AL - 25 D - 40 B - At beginning/cricopharynx 15 cm from upper incisors A- At Arch of aoa 25cm from upper incisors L- At Left Bronchus 25 cm from upper incisors D- At Diaphragm 40cm from upper incisiors", 'role': 'assistant'}]