This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System, Subject name: Physiology
[{'content': "A 70-year-old man presents with a 16-week history of progressive dysphagia, and recurrent pneumonia episodes. He also has palpable stony hard neck nodes on examination. Diagnosis is? \nSelect and explain. \nA. Carcinoma of the esophagus, B. Achalasia Cardia, C. Diffuse esophageal spasm, D. Zenker's diverticulum", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A Carcinoma of the esophagusRef: Bailey and Love, 26th ed. page 1004Esophageal cancer presents with mechanical symptoms, principally dysphagia, but sometimes also regurgitation. The main feature for malignancy in this case is stony hard consistency of neck Lymph nodes.', 'role': 'assistant'}]