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': 'First antibody response is mediated by ? \nSelect and explain. \nA. IgE, B. IgM, C. IgA, D. IgD', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., IgM", 'role': 'assistant'}]