This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Interstitial Lung Disease, Subject name: Medicine
[{'content': 'BAL of a patient shows foamy macrophages with decreased CD4: CD8 ratio. What is the diagnosis? \nSelect and explain. \nA. Sarcoidosis, B. Hypersensitivity pneumonitis, C. Organising pneumonia, D. Diffuse alveolar hemorrhage', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Organising pneumonia Foamy macrophages in BAL with low CD4: CD8 ratio Hypersensitivity pneumonitis Marked lymphocytosis Sarcoidosis Marked lymphocytosis with CD4: CD8 ratio of >3.5 Diffuse alveolar hemorrhage Hemosiderin laden macrophages', 'role': 'assistant'}]