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: 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: It is associated with an oesophagal web in post cricoid region and 10% patients develops post cricoid carcinoma.