Explanation:
The top left box- B,
Far left box- A,
Bottom box- it’s either C or E but ai am pretty sure it’s E
Answer:
The first heart sound (S1) represents closure of the atrioventricular (mitral and tricuspid) valves as the ventricular pressures exceed atrial pressures at the beginning of systole (point a). S1 is normally a single sound because mitral and tricuspid valve closure occurs almost simultaneously.
Explanation: