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
Following is true regarding opening snap : 
Select and explain. 
A. It is a high-pitched diastolic sound, B. It s due to opening of stenosed aoic valve, C. It indicates pulmonary aerial hypeension, D. It preceedes the aoic component of second hea sound
A: It is a high-pitched diastolic sound
Answer: A: It is a high-pitched diastolic sound 
Explanation: Answer is A (It is a high pitched diastolic sound) Opening snap is brief high pitched sound heard in early diastole. Opening snap brief high pitched sound heard in early diastole (Ejection sound are heard in systole) It is usually due to stenosis of an (A.V.) most often mitral value. It follows second hea sound, A2 by 0.05 to 0.12 sec. It is generally best heard at lower left sternal border and radiates well to the base of hea It is best heard during expiration The time interval between Az and Os varies inversely with the severity of MS. It is followed by low pitched rumbling diastolic murmur Note: O.S. may also be audible in tricuspid stenosis O.S. of tricuspid stenosis occurs later in diastole than the mitral O.S. Opening snap indicates that : M.S. is organic (and significant)Q Valve cusp4 are pliable e - High atroventricular pressure gradient is present - Severe, AR, MR, AF, SABE are absent. e