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: Unknown
[{'content': 'Which of the following components is a potent neutrophil chemotactic agent? \nSelect and explain. \nA. C 1, B. C 2, C. C5a, D. C789 complex', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C5a promotes chemotaxis. The complement components C l, C2, and the C789 complex do not promote chemotaxis.', 'role': 'assistant'}]