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: Sub-Commander T'Pol:  Has it occurred to you what 's going to happen if Captain Archer fails ? If Earth is destroyed ?
Commander Charles 'Trip' Tucker III: Every day .
Sub-Commander T'Pol: Good . Then you 've already come to the conclusion that without Humanity , there 's no one to combat these Sphere Builders . Their Expanse will continue to grow , encompassing one system after another , including Vulcan . Your world is no longer the only _ one _ in jeopardy .

world