Choose the correct pathway on the transmission of impulse in the heart beat.
a) AV-node → SA-node → Bundle of His → Purkinje fibres
b) SA-node → AV-node → Bundle of His → Purkinje fibres
c) SA-node → Bundle of His → AV-node → Purkinje fibres
d) AV-node → Bundle of His → SA-node → Purkinje fibres