This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Stomach & Duodenum, Subject name: Surgery
A 79-year-old retired opera singer presents with dysphagia, which has become progressively worse during the last 5 years. He states that he is sometimes aware of a lump on the left side of his neck and that he hears gurgling sounds during swallowing. He sometimes regurgitates food during eating. What is the likely diagnosis? 
Select and explain. 
A. Carcinoma of the esophagus, B. Foreign body in the esophagus, C. Plummer-Vinson (Kelly-Patteson) syndrome, D. Zenker's (pharyngoesophageal) diverticulum
D: Zenker's (pharyngoesophageal) diverticulum
Answer: D: Zenker's (pharyngoesophageal) diverticulum 
Explanation: A Zenker's (pharyngoesophageal) diverticulum is a mucosal outpouching through the triangular bare area between the cricopharyngeus muscle and the inferior constrictor muscle of the pharynx (Killian's triangle). Most present on the left side of the neck.