This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Medicine
[{'content': "Retrocardiac lucency with air-fluid level is seen in \nSelect and explain. \nA. Hiatus hernia, B. Distal end esophageal obstruction, C. Eventration of diaphragm, D. Zenker's diveiculum", 'role': 'user'}, {'content': 'Answer: A \nExplanation: The gastric fundus when displaced above the diaphragm, presents as a retrocardiac mass on a chest radiograph. The presence of an air-fluid level in the mass suggests the diagnosis. ref - Harrisons internal medicine 20e pg 2211', 'role': 'assistant'}]