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': "The feature of JVP in cardiac tamponade is: \nSelect and explain. \nA. Prominent x descent with prominent 'y'descent, B. Prominent x descent with absent 'y' descent, C. Absent x descent with prominent 'y' descent, D. Absent x descent with absent 'y' descent", 'role': 'user'}, {'content': "Answer: B \nExplanation: B i.e. Prominent X descent with absent 'Y' descent", 'role': 'assistant'}]