Defective semilunar valve can change the sound ‘dub’ to
Lub
Shub
Shhh
Khrrr
As we have learnt:
1. First sound S1- The first sound is ‘lubb’. It is a slow pitch sound created by the closure of the tricuspid and bicuspid valves at the beginning of ventricular systole
2. Second sound S2 - It is a highly pitched and sharper sound called ‘dubb’. This sound is a result of closure of semilunar valves and it marks the end of ventricular systole
So, Defective semilunar valve can change the sound ‘dub’ to ‘Shhh'. Hence, the correct answer is option c.