This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General, Subject name: Medicine
[{'content': 'Neisseria infection is characteristic of deficiency of: \nSelect and explain. \nA. C2, B. C3, C. C4, D. C5', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. D. C5* The best-documented genetic association with meningococcal disease is complement deficiency, chiefly of the terminal complement components (C5-9), properdin, or factor D; such a deficiency increases the risk of disease by up to 600- fold and may result in recurrent attacks.* Complement components are believed to be important for the bactericidal activity of serum, which is considered the principal mechanism of immunity against invasive meningococcal disease.', 'role': 'assistant'}]