This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Radiology Q Bank, Subject name: Radiology
[{'content': '20 years old male patient came to ER with severe dyspnoea. On examination, there is severe tachycardia, hypotension with distended neck veins. Chest x-ray is given below. Diagnosis is? \nSelect and explain. \nA. Simple pneumothorax, B. Tension pneumothorax, C. Bullous emphysema, D. Bronchogenic cyst', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Tension pneumothoraces occur when intrapleural air accumulates progressively in such a way as to exe positive pressure on mediastinal and intrathoracic structures. It is a life-threatening occurrence requiring both rapid recognition and prompt treatment to avoid a cardiorespiratory arrest. A non-tension pneumothorax is properly called a simple pneumothorax.', 'role': 'assistant'}]