This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
Most common cause of Air bronchogram 
Select and explain. 
A. Pulmonary edema, B. Consolidation, C. Hyaline membrane disease, D. Alveolar cell carcinoma
B: Consolidation
Answer: B: Consolidation 
Explanation: All the above are causes of AIr bronchogram.
M/C cause is consolidation.