The characteristic of a function is that for each input you there is only one output.
First line: you have 2 inputs of 2, but each has different output, so is not a function.
Second line has 2 inputs of 3, but each has a different output, so is not a function.
Third line is fine.
The fourth line has 2 inputs of 5s but each one has a different output, so it also can't be a function.
Thus, the answer is the third choice: 4 5 3 8 2 2
