This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'An iron protein complex which combines with oxygen and carbon dioxide is: \nSelect and explain. \nA. Hematin, B. Hemosiderin, C. Hemoglobin, D. Oxyhemoglobin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Hemoglobin (sometimes abbreviated as Hb) is a complex protein found in red blood cells that contains an iron molecule.\xa0\nThe main function of hemoglobin is to carry oxygen from the lungs to the body tissues, and to exchange the oxygen for carbon dioxide, and then carry the carbon dioxide back to the lungs and where it is exchanged for oxygen.\xa0\nThe iron molecule in hemoglobin helps maintain the normal shape of red blood cells.', 'role': 'assistant'}]