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 murmur of hypertropic obstructive cardio myopathy is decreased in which of the following- \nSelect and explain. \nA. Supine position, B. Standing position, C. Valsalva maneuver, D. Amyl nitrate inhalation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]