This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Imaging of Pleural Disease, Subject name: Radiology
A case of road traffic injury presented with chest and abdominal pain. Chest X-ray is shown below. What is the diagnosis? 
Select and explain. 
A. Hemothorax, B. Pneumothorax, C. ARDS, D. Fat embolism
B: Pneumothorax
Answer: B: Pneumothorax 
Explanation: Ans. (b) Pneumothorax.The diagnosis of pneumothorax is established by demonstrating the outer margin of the visceral pleura (and lung), known as the pleural line, separated from the parietal pleura (and chest wall) by a lucent gas space devoid of pulmonary vessels. Notice the same on the image on the right side.