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: Pediatrics
[{'content': 'Bart hemoglobin consist of \nSelect and explain. \nA. Four γ chains, B. Four β chains, C. Two γ chains + Two β chains, D. Two α chains + Two γ chains', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Bart hemoglobin is tetramer of four γ chains.', 'role': 'assistant'}]