What is the correct sequence of the origin and conduction of the heartbeat?

• A
  $AV$ node $\rightarrow$ Bundle of $His$ $\rightarrow$ $SA$ node $\rightarrow$ Purkinje fibers
• B
  $SA$ node $\rightarrow$ Purkinje fibers $\rightarrow$ $AV$ node $\rightarrow$ Bundle of $His$
• C
  Purkinje fibers $\rightarrow$ $AV$ node $\rightarrow$ $SA$ node $\rightarrow$ Bundle of $His$
• D
  $SA$ node $\rightarrow$ $AV$ node $\rightarrow$ Bundle of $His$ $\rightarrow$ Purkinje fibers