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': 'An increase in which of the following parameters will shift the O2 dissociation curve to the left - \nSelect and explain. \nA. Increased temperature, B. Increased partial pressure of CO2, C. Increased 2, 3 DPG concentration, D. Increased oxygen affinity of hemoglobin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Hb-O2 dissociation curve shift to left indicates more affinity of Hb to O2 and thus less delivery of O2 to tissues.\nShift to left seen in\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Increased pH\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Decreased 2,3 DPG, temperature, PCO2\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 HbF (Fetal)\nShift to right seen in\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Decreased pH\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Increased 2,3DPG, temperature, PCO2\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 HbS (Sickle cell)', 'role': 'assistant'}]