Option 2 is the correct answer.
A function is a relation (rule) that assigns each element in the domain to exactly one element in the range.
Essentially, a set of domain contains the input values that will be used to determine its corresponding functional (output) values.
A function can only take on one output for each input. We cannot plug in a value and get out two values.
Therefore, the correct answer is Option 2.
Please mark my answers as the Brainliest, if you find this helpful :)