This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdomen and pelvis, Subject name: Anatomy
[{'content': 'What is the commonest site of esophageal carcinoma ? \nSelect and explain. \nA. lower end of oesophagus, B. upper end of oesophagus, C. middle third of oesophagus, D. thorasic pa of oesophagus', 'role': 'user'}, {'content': "Answer: A \nExplanation: The lower end of the oesophagus is also prone to inflammation or ulceration by regurgitation of acid from the stomach. It is the commonest site of oesophageal carcinoma. Ref : B D Chaurasia's Human Anatomy , seventh edition , volume 2 , pg.no.,273.", 'role': 'assistant'}]