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What causes the first heart sound? When does this occur?
Multiple Choice
Closure of the atrioventricular valves soon after the beginning of ventricular systole
Closure of the semilunar valves soon after the beginning of ventricular systole
О
Closure of the atrioventricular valves at the beginning of ventricular diastole
о
Closure of the semilunar valves at the beginning of ventricular diastole



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