This is known as Onesky.
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The question does not make sense please type in comments and tell me
Answer:
Hemoglobin.pulmonary artery.
Explanation:
1. about hemoglobin.Hemoglobin is the protein inside red blood cells. It carries oxygen.
2. about pulmonary artery.The pulmonary artery is a big artery that comes from the heart. It splits into two main branches, and brings blood from the heart to the lungs. At the lungs, the blood picks up oxygen and drops off carbon dioxide. The blood then returns to the heart through the pulmonary veins.
3. There exist a concentration difference of carbon dioxide and oxygen inside the alveoli and capillaries due to which the diffusion of the two gases takes place. The carbon dioxide moves from the blood to the alveoli sac and the oxygen moves from the sacs to the blood.
