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: Eli Vance:  Why did n't they listen ? We tried to warn them .
Scientist 2: I never thought I 'd see a resonance cascade , let alone create _ one _ .
Eli Vance: Gordon , you 're alive ! Thank God for that hazard suit . I 'm afraid to move him and all our phones are out . Please get to the surface as soon as you can and let someone know we 're stranded down here . You 'll need me to access the retinal scanners . I 'm sure the rest of the science team will gladly help you .

cascade