Identify the option showing the correct labeling for $p$,$q$,$r$ and $s$ with reference to the conducting system of the human heart.

• A
  $p$-Interventricular septum,$q$-$AVN$,$r$-Bundle of His,$s$-$SAN$
• B
  $p$-$SAN$,$q$-$AVN$,$r$-Bundle of His,$s$-Interventricular septum
• C
  $p$-$AVN$,$q$-$SAN$,$r$-Interventricular septum,$s$-Bundle of His
• D
  $p$-Bundle of His,$q$-$SAN$,$r$-Interventricular septum,$s$-$AVN$