Which one of the following is a matching pair?

Q. Which one of the following is a matching pair?

A.            Luub- sharp closure of AV valves at the beginning of ventricular systole

B.            Dup- sudden opening of semilunar valves are the beginning of ventricular diastole

C.            pulsation of the radial artery-valves in the blood vessels

D.            initiation of heart beat- purkinje fibres

Answer: Luub- sharp closure of AV valves at the beginning of ventricular systole