Answer:
Number 9 is not a function number 12 is a function
Explanation:
Number 9 is not a function because it did not pass the vertical line test which you have to hold a tool vertically and see if there are a line that touches it more than once if it does then it fails and it is not a function and if it only touches once then it passes and is a function but number 9 does touch more than one time so it is not a function
Number 12 is a function because it pass the vertical line test
Hope this helps!