This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Valvular hea diseases, Subject name: Medicine
[{'content': 'Soft S1 is seen in all except: \nSelect and explain. \nA. First degree hea block, B. AR, C. Calcified valve, D. Mild MS', 'role': 'user'}, {'content': 'Answer: D \nExplanation: MS: | Trans-valvular gradient, faster opening and faster elastic recoil - l/t loud S1 Option A- Causes bradycardia l/t soft S1 Option B- Blood comes black in LV, so increased volume in L.V during diastole d/t defective aoic valve closure blood comes back into the ventricle.The gradient stas reducing so l/t soft S1 sound. Option C -S1 become Soft once valve get calcified.', 'role': 'assistant'}]