Answer:
B
Explanation:
hope it helps:)))))))))))))))))))
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.
Answer:
no
Explanation:because they will find new ways to survive in the environment
The chemical reaction could be vary with the condition but the nuclear decay rate is constant, here the option A is the right option.
