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': "Typical JVP finding in cardiac tamponade- \nSelect and explain. \nA. Absent 'Y' descent, B. Prominant 'a' wave, C. Absent 'a' wave, D. Prominent 'Y' wave", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]