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: Special Agent Leroy Jethro Gibbs:  Marine gets murdered serving his country . He deserves a throuogh investigation .
NCIS Asst. Director Leon Vance: And he 'll get _ one _ . But the Sec Nav want * us * to handle the case . Who do you think I should send ?

investigation