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: Medicine
[{'content': 'A post-operative cardiac surgical patient developed sudden hypotension, raised central venous pressure, pulsus paradoxus at the 4th post operative hour. The most probable diagnosis is: \nSelect and explain. \nA. Excessive mediastinal bleeding, B. Ventricular dysfunction, C. Congestive cardiac failure, D. Cardiac tamponade', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Answer is D (Cardiac tamponade) Features of rising pressure, falling aerial pressure and pulsus paradoxus following surgery on the hea leads us to the diagnosis of cardiac tamponade.', 'role': 'assistant'}]