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: Microbiology
[{'content': 'Complement binding immunoglobin via the classical pathway is \nSelect and explain. \nA. IgG & IgM, B. IgG & IgA, C. IgG & IgD, D. IgD & IgE', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]