This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Physiology
[{'content': 'Oxygen affinity increases with \nSelect and explain. \nA. Carbon monoxide, B. Acidosis, C. Hypoxia, D. Anemia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Oxygen affinity increases with left shift of O2-Hb dissociation curve. It is seen in fetal hemoglobin and carbon monoxide.Oxygen affinity decreases with right shift of O2-Hb dissociation curve. It is seen in hypoxia, high altitude, anemia, acidosis, and exercise.Ref: Medical physiology for UG students, Indu Khurana, page: 328', 'role': 'assistant'}]