This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory Infections, Subject name: Social & Preventive Medicine
What is true regarding Diphtheria ? 
Select and explain. 
A. Nasal carriers are more dangerous than cases, B. Immunization prevent carrier state, C. Cases are most impoant as source of infection, D. Hemagglutination test has been replaced by Schick test
A: Nasal carriers are more dangerous than cases
Answer: A: Nasal carriers are more dangerous than cases 
Explanation: Diphtheria Causative agent - Corynebacterium diphtheria, a gram + bacilli, non-motile organism . Incubation period 2-6 days Immunization does not prevent carrier state. Carriers are more impoant source of infection (dangerous) than cases.