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: Helen Chapel:  What the hell 's this ' transponder ' he keeps talking about ?
Fay Schlob Dumbly DeVay Cochran: It 's a transmitter that sends out a constant homing signal so that , in the event of a crash , they 'll be sure to find us .
Helen Chapel: And if we do n't have _ one _ ?
Fay Schlob Dumbly DeVay Cochran: Well , what 's the nautical equivalent of ' needle in a haystack ? '

transponder