This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
[{'content': 'HbA2 has \nSelect and explain. \nA. a 2 ss 2, B. a 2 g 2, C. a 2 d 2, D. g 2 d 2', 'role': 'user'}, {'content': 'Answer: C \nExplanation: HbA2 contains 2 alpha and 2 delta chains.Adult Hb referred 5as HbA contains 2 alpha and 2 beta chains.Foetal Hb ie HbF contains 2 alpha and 2 gamma chains.Ref: Textbook of medical physiology by N Geetha, 2nd edition, page no. 74', 'role': 'assistant'}]