This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Esophagus Applied Anatomy: GERD, Subject name: Pathology
A 20-year-old woman presents with a 2-year history of difficulty swallowing and increasing fatigue. A CBC shows Iron-deficiency anemia. Upper endoscopy reveals an annular narrowing in the upper third of the esophagus. A mucosal biopsy shows no evidence of inflammation or neoplasia. Which of the following is the most likely diagnosis? 
Select and explain. 
A. Achalasia, B. Barrett esophagus, C. Diveiculum, D. Esophageal web
D: Esophageal web
Answer: D: Esophageal web 
Explanation: Plummer-Vinson syndrome is characterized by: Cervical esophageal web/ rings Mucosal lesions of the mouth and pharynx Iron-deficiency anemia.