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': 'Most abundant complement in the body \nSelect and explain. \nA. C1, B. C2, C. C3, D. C4', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C3 is the most abundant complement.', 'role': 'assistant'}]