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: Medicine
[{'content': 'Adult haemoglobin consists of which one of the following tetramer of chains ? \nSelect and explain. \nA. 2α+ 2β, B. 2α+ 2δ, C. 2β + 2γ, D. 2α + 2γ', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]