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
BAL of a patient shows foamy macrophages with decreased CD4: CD8 ratio. What is the diagnosis? 
Select and explain. 
A. Sarcoidosis, B. Hypersensitivity pneumonitis, C. Organising pneumonia, D. Diffuse alveolar hemorrhage
C: Organising pneumonia
Answer: C: Organising pneumonia 
Explanation: 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