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': 'C3b is converted to C3 convertase by \nSelect and explain. \nA. Factor D, B. Factor H, C. Factor I, D. All the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: C3b is converted to C3 convertase by Factor B, Factor D, Properdin.', 'role': 'assistant'}]