Which of the following produces the first heart sound?
The closing of the valves between the ventricles and the body
The opening of the valves between the atria and the ventricles
The closing of the valves between the atria and ventricles
The opening of the valves between the ventricles and the body
The closing of the valves between the ventricles and the body
The opening of the valves between the atria and the ventricles
The closing of the valves between the atria and ventricles
The opening of the valves between the ventricles and the body