This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Valvular Heart Disease, Subject name: Medicine
[{'content': 'Pulsus paradoxus is seen in? \nSelect and explain. \nA. Cardiac tamponade, B. Mitral regurgitation, C. Aortic regurgitation, D. Mitral stenosis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: ANSWER:(A)Cardiac tamponadeREF:Harrison 18th Ed chapter 227See previous question', 'role': 'assistant'}]