Answer:
C. percent saturation of hemoglobin with O2 in systemic arterial blood
Explanation:
Hemoglobin is a protein that contains 4 heme groups that have iron (Fe) as its central atom, which is the binding site for the oxygen molecule (the oxygen binds with the iron atom), so each hemoglobin molecule can bind up to 4 oxygen molecules. This oxygenated blood is the arterial blood, which becomes bright red because of this binding, and is the blood that carries that oxygen to all the tissues.
Sometimes, conditions like temperature, pH, or CO2 concentration can affect the structure of the hemoglobin, and that can make it more difficult for oxygen to bind to heme group, so in those cases that would have a direct effect on the percentage of saturated hemoglobin (hemoglobin binded with oxygen).
