Which relation is not a function? {(1,5), (2,6), (3,6), (4,7)}
{(4,7, (2,1), (-3,6), (3,4)}
{(-1,6), (1,3), (2,5), (1,7)}
{(-1,2), (0,5), (5,0), (2,-1)}

C

Step-by-step explanation:

The X value repeats itself

Step-by-step explanation: In order for a function not to be a relation,

each x-coordinate must correspond to more than one y-coordinate.

Notice that in third relation, the 1 pairs with a 3

in one case  and it pairs with a 7 in the other case.

Since each x-coordinate pairs with more than one y-coordinate,

this relation is not a function but the other ones are functions.

What are the answer choices?