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': 'Haemoglobin is the major buffer in blood, bicarbonate ions diffuses out of erythrocyte into plasma in exchange of: \nSelect and explain. \nA. Potassium, B. Phosphate, C. Carbonic acid, D. Chloride ion', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]