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
Which of the following region is involved in Plummer-Vinson syndrome? 
Select and explain. 
A. Pyriform sinus, B. Post cricoid region, C. Valleculae, D. Posterior pharyngeal wall
B: Post cricoid region
Answer: B: Post cricoid region 
Explanation: 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)