There is a rule for functions:
One input(x-value) can only have one output(y-value).
If one input has more than one output, it's not a function.
(This doesn't apply to outputs, one output can have more than one input and still be a function)
Option 1: It is not a function because the inputs 9 and 10 have more than one output
Option 2: It is not a function because the input 3 has more than one output
Option 3: It is a function because each input has only one output
Option 4: It is not a function because the input 5 has more than one output
