A function can be determined if every x-value has a different y-value so...
The only possible answer is A.
The other answer choices have the same x-values with multiple y-values like:
b. (-6, 0) and (-6, -2) <<<They both have -6 as the x but the y's are different
d. (7, 5) and (7,3) <<<They both have 7 as the x but the y's are different
Hope this helped!
(The reason I didn't mention c was because this one doesn't make sense at all. It should have been the first one you marked as wrong)