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: Microbiology
[{'content': 'Most important source of infection for meningococci: \nSelect and explain. \nA. Case, B. Subclinical infection, C. Carriers, D. Latent case', 'role': 'user'}, {'content': 'Answer: C \nExplanation: During periods of endemic disease, about 10% of the general population harbour Neisseria meningitidis in the nasopharynx.\xa0\nSince N. meningitidis is a strict human pathogen and most patients have not been in contact with other cases, asymptomatic carriers are presumably the major source of the pathogenic strains.', 'role': 'assistant'}]