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': 'Bronchial secretion secretes: \nSelect and explain. \nA. IgA, B. IgE, C. IgM, D. IgG', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (IgA) (140 - CP) (89-AN 7th)IgA - Principal immunoglobulin that appears in the sero-mucinous secretions such as milk,, saliva, tears, nasal fluids, sweat and secretions of respiratory, intestinal and genital tracts,', 'role': 'assistant'}]