Not functions: Option 1 and 3.
Functions: Options 2 and 4.
Which ones are functions?
A function is a relation where each input is mapped into a single output. So, if we can see a input being mapped to two or more outputs, then this is not a function.
With this in mind, we can see that:
Options 1 and 3 have multiple outputs for the same inputs, thus, these are not functions.
Options 2 and 4 have one output per input, so these are functions.