Definition: In this task, you will use your knowledge about language (and common sense) to determine what element the marked number refers to. The numbers are marked with two underlines around them, like: _ number _. Your answer should be chosen from the given text, and should not contain other words.
Input: Kyoichi Kanzaki:  This universe was born approximately 15 billion years ago . In this galaxy alone , there are approximately 200 billion stars . Somewhere in space , at this very moment , an enormous battle might be taking place , _ one _ that will decide the fate of two warring planets . But , regardless of what might be happening , the seasons still change .

battle