Not sure if your q is multiple choice but it should be drain line.
Answer:
B. Carbon dioxide is carried through the blood vessels back to the lungs.
Explanation:
The answer to this anatomy question is simple. The one that sets the pace of the heart rate is called the sinoatrial node, a group of cells located <span>in the wall of the </span>right atrium<span> of the </span>heart<span>.</span>
