The correct option is A SA node → AV node → bundle of His →Purkinje fibres → heart muscles
The initiation of heartbeat or the cardiac cycle begins when the deoxygenated blood enters the right atrium which stimulates the SAN to undergo depolarisation. The electrical signal travels from the SA node through muscle cells in the right and left atria. The signal triggers the muscle cells that make your atria contract. The atria contract, pumping blood into your left and right ventricles. After electrical impulse is sent from the sinoatrial (SA) node to the atrioventricular (AV) node, the bundle of His quickly transmits the impulse to the left and right bundle branches and into the ventricles through Purkinje fibres, resulting in a synchronised contraction of the ventricles.