A relation R exists such that for every input (x), the output is −x. Which statement about the relation R is correct?
The relation R is not a function because there is at least one output for each input.
The relation cap r is not a function because there is at least one output for each input.

The relation R is not a function because there is more than one output for each input.
The relation cap r is not a function because there is more than one output for each input.

The relation R is a function because the output is the opposite of the input.
The relation cap r is a function because the output is the opposite of the input.

The relation R is a function because for each input there is exactly one output.