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': 'Dysphagia in Plummer Vinson syndrome is due to \nSelect and explain. \nA. Post cricoid region commonly involved in web formation, B. Web is common in lower region, C. It is due to abnormal vessels, D. Web is common in middle zone', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e. Post cricoid region commonly involved in web formation", 'role': 'assistant'}]