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: Medicine
[{'content': 'What is the diagnosis? <img src=" /> \nSelect and explain. \nA. Pneumothorax, B. Emphysema, C. Bronchiectasis, D. Cardiomegaly', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Emphysema is commonly seen on CXR as diffuse hyperinflation with increased lucency, flattening of diaphragms, increased anteroposterior, increased retrosternal spaceRef: Harrison 19e pg: 308, e-5', 'role': 'assistant'}]