Concerning Heart Sounds, Which of the Following Is Correct

Multiple Choice

Concerning heart sounds, which of the following is correct?

A) The first heart sound occurs at the beginning of ventricular systole.
B) The second heart sound is heard when the AV valves are closing.
C) The first heart sound is the sound of the semilunar valves closing.
D) The second heart sound occurs when blood flows into the superior vena cava.
E) The first heart sound occurs at the beginning of ventricular diastole.