ANSWER:
True/Yes
EXPLANTION:
A function only works when one input (x) is paired with only one output (y). One the table each input is paired with only one output so that makes it a true/yes.
FUN FACT:
A function can still work when the output is paired with more then one input, but cannot work if the input is paired with more then one output.
I hoped this helped and have a great day ;:)