The answer is A because the heart pumps blood from the heart through pulmonary artery that is low in oxygen and high in carbon dioxide concentration, to the lungs.
The answer would be chromosomes
I think this is what you are referring to.
Hope this helps.
StMary's a good day for me and you are the kids going ❤️❤️ a good time☺️☺️
Adenine,guanine,cytosine,and uracil