Which of the following events does not take place during a ventricular systole
i. Due to the ventricular systole, ventricular pressure decreases.
ii. During the end of ventricular systole the semilunar valves open up.
iii. During the start of the ventricular systole the bicuspid and tricuspid valves close
iv. Due to the closure of the atrio-ventricular valves, dup sound is produced.