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': 'Immunoglobulin crossing placenta is \nSelect and explain. \nA. IgM, B. IgA, C. IgG, D. IgD', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]