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 causes 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: Ans. Emphysema