Answer:
a. in the bottom of the atrium just above the ventricles
Step-by-step explanation:
AV node -
It helps to control the heart rate , it serves as an electrical relay station , reduces the electrical current which is sent by the SA node .
The location of the AV node , is at the lower back section of the inter atrial septum , and conducts the electrical impulse normally from the atria to ventricles .