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
The first heart sound is loud in all the following except 
Select and explain. 
A. Mitral stenosis, B. Anemia, C. Thyrotoxicosis, D. Mitral valve calcification
D: Mitral valve calcification
Answer: D: Mitral valve calcification 
Explanation: None