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: Physiology
[{'content': 'Fetal hemoglobin has a higher affinity for oxygen due to \nSelect and explain. \nA. Low affinity for 2, 3 DPG, B. Reduced pH, C. Increased release of carbon dioxide, D. Oxygen dissociation curve is shifted to right', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Make it very clear in mind that the higher affinity of fetal hemoglobin for oxygen is due to the low affinity of HbF for 2,3 - DPG (not due to decreased 2, 3-DPG concentration). HbF does not combine to 2, 3-DPG as avidly as adult hemoglobin.\n"Fetal hemoglobin is left - shifted because it has a low affinity for DPG". — Principles of medical physiology\n"It is worth noting that DPG does not combine with fetal hemoglobin. That is perhaps one reason why HbF has a greater affinity for oxygen than adult hemoglobin (HbF)".\xa0— Understanding of medical physiology\n"Fetal hemoglobin binds less 2-3 DPG it has consequently a greater affinity for O2". _\xa0Pediatric physiology\nAll other textbooks have mentioned the same thing.\nSo, the high affinity of HbF to O2 is due to the low affinity of HbF for 2, 3 DPG (and not due to decreased 2, 3-DPG concentration).\nHowever, amongst the given options, option a is the best answer here because, although there is no decrease in concentration of 2, 3-DPG, because of low affinity for 2, 3-DPG, HbF behaves as if 2, 3-DPG levels are low.\n"Fetal hemoglobin has considerably less affinity for 2, 3-DPG than does adult hemoglobin. In human blood, the affinity of fetal hemoglobin for 2, 3-DPG is only about 40% that of adult hemoglobin. This makes fetal hemoglobin behave as if 2, 3-DPG levels are low; therefore, the oxygen dissociation curve is shifted to the left". — Clinical physiology in childhood', 'role': 'assistant'}]