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: Social & Preventive Medicine
After vaccination against Japanese encephalitis immunity developes in - 
Select and explain. 
A. 30 days, B. 7 days, C. 10 days, D. 21 days
A: 30 days
Answer: A: 30 days 
Explanation: None