This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thorax, Subject name: Anatomy
[{'content': 'Constrictions in Esophagus by aoa is present at distance of from incisor \nSelect and explain. \nA. 15 cm, B. 25cm, C. 30 cm, D. 40 cm', 'role': 'user'}, {'content': "Answer: B \nExplanation: Construction of oesophagus at the following levels 15 cm-crossed by cricopharyngeus 22.5 cm-crossed by aoa 27.5 cm-crossed by left bronchus 37.5 cm-pierces the diaphragm All from incisor teeth BD CHAURASIA'S HUMAN ANATOMY VOL.1,PAGE NO 282", 'role': 'assistant'}]