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: Headmaster:  Now this object I 'm holding here is call ... well some of you may have seen _ one _ before , it 's called a book . You may have seen one on television .

book