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': 'The predominant immunoglobulin in saliva is \nSelect and explain. \nA. IgA, B. IgD, C. IgE, D. IgG', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]