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
Chest X-ray shows opacity after blunt trauma, most likely diagnosis is – 
Select and explain. 
A. Haemothorax, B. Pneumothorax, C. Pneumonia, D. Pulmonary embolism
A: Haemothorax
Answer: A: Haemothorax 
Explanation: Amongst the given options hemothorax and pneumonia (consolidation) produce opacity on chest X-ray. Pneumonia has nothing to do with blunt chest trauma, while hemothorax is common after blunt chest trauma. Therefore, best answer here is hemothorax.
Pneumothorax causes hypertranslucency (not opacity).