Question: Each red blood cell Multiple Choice has a variable amount of hemoglobin and therefore each cell carries a different amount of oxygen. contains one molecule of hemoglobin and about 250 million atoms of iron which bond to up to 250 million oxygen atoms. has a constant amount of hemoglobin but a variable amount of iron and therefore each cell carries a different amount of oxygen. contains about 250 million hemoglobin molecules and so can carry at least one billion molecules of oxygen. contains four molecules of hemoglobin molecules and so can carry up to 4 molecules of oxygen. Need Assignment Help?