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': 'Which of the following immunoglobulins has the highest mean serum concentration in humans? \nSelect and explain. \nA. IgA, B. IgD, C. IgG, D. IgM', 'role': 'user'}, {'content': 'Answer: C \nExplanation: IgG is the most abundant class of immunoglobulins in the serum, comprising about 80% of the total serum immunoglobulin.\nThere are four IgG subclasses IgG1, IgG2, IgG3, and IgG4—so numbered according to their decreasing concentrations in serum.\n\nParija SC. Textbook of Microbiology & Immunology. Elsevier Health Sciences; 2014. Page:96', 'role': 'assistant'}]