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
Area of mitral orifice in adults is: 
Select and explain. 
A. 6-8 cm2, B. 5-2 cm2, C. 4-6 cm2, D. 1-4 cm2
C: 4-6 cm2
Answer: C: 4-6 cm2 
Explanation: Answer is C (4-6 cm2): The normal area of mitral valve is 4-6 em2. Mitral Valve & pathology Area Normal Mitral Valve 4-6 cm2Q Mild Mitral Valve < 2 cm? Severe Mitral Stenosis < 1.3 cm2Q Critical Mitral Stenosis < 1 cm2 Q Aoic Valve & pathology Area Normal Aoic Valve 2.6 - 3.5 cm2Q Mild Aoic Stenosis 1.5 - 2 cm2 Moderate Aoic Stenosis 1 - 1.5 cm2 Severe Aoic Stenosis < 0.8cm2