This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Medicine
Two students from a university dormitory building have contracted meningitis due to Neisseria meningitides. Which of the following students in the dormitory are most likely to benefit from chemoprophylaxis? 
Select and explain. 
A. everybody in the dormitory, with oral amoxicillin, B. close contacts only, with oral amoxicillin, C. everybody in the dormitory, with oral rifampin, D. close contacts only, with oral rifampin
D: close contacts only, with oral rifampin
Answer: D: close contacts only, with oral rifampin 
Explanation: Although only close contacts need chemo-prophylaxis, it is sometimes given more widely than recommended because of community concern. Meningococcal vaccine is effective against serotype A and C, and will prevent late secondary infection in close contacts. Ciprofloxacin or ofloxacin are alternatives to rifampin.