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
Yellow fever aedes agypti index should be ? 
Select and explain. 
A. <1%, B. < 5%, C. <10%, D. < 20%
A: <1%
Answer: A: <1% 
Explanation: Ans. is 'a' i.e., < 1%