Which of the relationships below is a function?

a. (6,3), (5,2), (6,8), (0,7)

b. (8,2), (1,7), (-1,2), (1,9)

c. (4,3), (3,0), (-1,3), (2,7)

d. (7,1), (0,0), (6,2), (0,4)

First: a function is an input connected to one and only one output.

I would say that C, (4,3), (3,0), (-1,3), (2,7), would be correct. You see, no inputs are repeating, unlike A, B, and D, which repeat