Which of the following best defines an input?

An input is the result of a relation or the function rule, usually the y-values in a set of ordered pairs or on a table or graph.
An input is a special type of relation for which there is a rule that pairs each input with exactly one output.
An input is a set of ordered pairs in which no y-value repeats.
An input is the value that determines another based on the relation or the function rule, usually the x-values in a set of ordered pairs or on a table or graph.

Question

Which of the following best defines an input?

 An input is the result of a relation or the function rule, usually the y-values in a set of ordered pairs or on a table or graph.
 An input is a special type of relation for which there is a rule that pairs each input with exactly one output.
 An input is a set of ordered pairs in which no y-value repeats.
 An input is the value that determines another based on the relation or the function rule, usually the x-values in a set of ordered pairs or on a table or graph.