Which one of the following is a correct matching pair?
A. Lubb - Sharp closure of AV valves at the beginning of ventricular systole
B. Purkinje fibers - Initiation of the heart beat
C. Dup - Sudden opening of semilunar valves at the beginning of ventricular diastole
D. Pulsation of the radial artery - Valves in the blood vessels