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
Amplifier for Japanese encephalitis ? 
Select and explain. 
A. Horse, B. Pigs, C. Dogs, D. Monkey
B: Pigs
Answer: B: Pigs 
Explanation: Ans. is 'b' i.e., Pigs