Which of the following relations is a function? A{(1, 3), (2, 3), (4,3), (9. 3)}

B{(1, 2), (1, 3), (1.4), (1,5)}

C{(5, 4), (-6, 5), (4, 5), (4, 0)}

D{(6,-1), (1, 4), (2, 3), (6, 1)}

The answer is a. to be a function there can’t be an x value that is the same to a different y value. so as an example (6,7) (3,2) (5,6) (6,3) is not a function because 6 appears 2 times as an x value but with different y values. but you can have the same y value.