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
The cause of homogenous opacity on X-ray is all except – 
Select and explain. 
A. Pleural effusion, B. Diaphragmatic Hernia, C. Massive consolidation, D. Emphysema
D: Emphysema
Answer: D: Emphysema 
Explanation: Emphysema produces blackening (not opacity) due to increased air.
Homogeneous opacity is produced by consolidation, pleural effusion, hemothorax and diaphragmatic hernia.