"C" in Science by HensleyB

Question 4

Fill the blank in the excerpt from Science below:

"It was conceived after a yogurt company in 2007 identified an unexpected defense mechanism that its bacteria use to fight off viruses. A birth announcement came in 2012, followed by crucial first steps in 2013 and a massive growth spurt last year. Now, it has matured into a molecular marvel, and much of the world—not just biologists—is taking notice of the genome-editing method ___, Science’s 2015 Breakthrough of the Year."