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': 'Immunoglobulin which is produced first by the fetus in response to infection:(1987) \nSelect and explain. \nA. IgG, B. IgA, C. IgM, D. IgD', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans: c (IgM)Ref: Ananthanarayan Micro, 7thed, p. 89 & 6th ed, p. 83, 84', 'role': 'assistant'}]