Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: Guangzhou, China (CNN) Zhiyong Xi is a man on a mission. He wants to rid China -- and potentially the world -- of mosquitoes, specifically the ones that carry devastating diseases like Zika and dengue. And he's doing it in the classic style of good versus evil. "We're building good mosquitoes that can help us fight the bad ones," the entomologist said in his 3,500-square-foot laboratory in Guangzhou, China. Decked out in white scrubs, Xi, a soft-spoken researcher from Michigan State University, gestures at hundreds of trays, each filled with about 6,000 squirming mosquito larvae. The room reeks of ground beef liver powder cut with yeast, a superfood for the tiny creatures.At this lab, technicians are breeding up to 5 million Aedes albopictus mosquitoes a weekThey're part of a plan to eliminate some of the common mosquito-borne diseases 
 Question:As is the case with _, most people infected with dengue fever don't know it, because they don't have symptoms.

Zika