Xavier and Yogender stay in the same hotel of the same university.Xavier develops infection with Group B meningococcus.After a few days Yogender develops infection due to Group C meningococcus.All the following are true statements except:

• A. Chemotheraphylaxis to all against both Group B and Group C
• B. Educate students about meningococcal transmission and take preventive measures
• C. Vaccine prophylaxis of contacts of Yogender
• D. Vaccine prophylaxis of contacts of Xavier