This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
[{'content': 'Complement binding immunoglobulin 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: IgM is paicularly effective at complement activation by binding to C1. IgG activates the classical pathway of the complement system, a cascade of immune protein production Ref: Ananthanarayan & Parker's textbook of microbiology 9th edition pf:98", 'role': 'assistant'}]