This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2019, Subject name: Microbiology
[{'content': 'N. meningitidis can be due to deficiency of this complement system: \nSelect and explain. \nA. C1-C4 deficiency, B. C5-C9 deficiency, C. C3 deficiency, D. C2 deficiency', 'role': 'user'}, {'content': 'Answer: B \nExplanation: C5 - C9 - MAC (membrane attack complex) deficiency can lead to increased risk of meningococcal disease. C1, C2, and C4 deficiencies are associated with pyogenic infections and rheumatologic disorders, paicularly systemic lupus erythematosus. C3 deficiency is also associated with pyogenic infections and rheumatologic disorders', 'role': 'assistant'}]