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 systolic ejection murmur in hypertrophic obstructive cardiomyopathy is diminished when a patient - \nSelect and explain. \nA. Performs the valsalva maneuver, B. Lies down, C. Inhales amyl nitrite, D. Stands up', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]