This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
Duration of second hea sound is 
Select and explain. 
A. 0.12 Sec, B. 0.1 Sec, C. 0.15 Sec, D. 0.2 Sec
A: 0.12 Sec
Answer: A: 0.12 Sec 
Explanation: The second sound lasts about 0.12 s, with a frequency of 50 Hz. It is loud and sharp when the diastolic pressure in the aoa or pulmonary aery is elevated, causing the respective valves to shut briskly at the end of systole.Ref: Ganong&;s Review of medical physiology 25th edition. Page: 542