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: Pathology
[{'content': 'The complement is fixed best by which of the following immunoglobulins - \nSelect and explain. \nA. IgG, B. IgM, C. IgA, D. IgD', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., IgMIgM is the most effective antibody to fix complement.", 'role': 'assistant'}]