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': 'Most important mediator of chemotaxis is: \nSelect and explain. \nA. C3b, B. C5a, C. C5-7, D. C2', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Role of different mediators in Inflammation', 'role': 'assistant'}]