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 most impoant meditor of chemotaxis among following is - \nSelect and explain. \nA. C3b, B. C5a, C. C567, D. C2', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., C5a", 'role': 'assistant'}]