This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oral cavity & Oesophagus, Subject name: ENT
[{'content': 'Which of the following region is involved in Plummer-Vinson syndrome? \nSelect and explain. \nA. Pyriform sinus, B. Post cricoid region, C. Valleculae, D. Posterior pharyngeal wall', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Predominantly, it affects females past 40 years. Barium swallow shows a web in the postcricoid region and the same can be seen on oesophagoscopy. It is due to subepithelial fibrosis in this region. (Ref: Textbook of diseases of ENT, PL Dhingra, 7th edition, pg no. 388)', 'role': 'assistant'}]