Which relation is a function?
a.
(6, 5), (1, 1), (6, 4)
b.
(0, 1), (2, 3), (2, 5)
c.
(8, –2), (–2, 5), (6, 0)
d.
(–2, 3), (–5, 9), (–5, 3)

Solutions 

A function is a relation between a set of inputs and a set of permissible outputs. "f(x) = ... " is a way of writing a function. Everything that goes into the function is put inside parentheses the (). 

The correct answer for the relation is a function is (C) 

(C) = (8, –2), (–2, 5), (6, 0)