Well I think is physics right? Like bones
Answer:
I am not sure but I think it is 2
Since the other answer got deleted, i'll just answer it for you.
a sinoatrial node is the main pacemaker that begins each heartbeat located in the junctions of superior vena cava and the right atrium. It signals from the node that spread through the atria and determines the heart rates.
The answer to this question is a volcaniclastic debris. A volcaniclastic debris are debris from the volcano that was transported either through air or wind to the land or surface. An example of volcaniclastic debris are ashes, rocks, cinders, and blocks.
