Answer: C
Step-by-step explanation: First, it's important to understand the definition of a function so we know how to solve the problem.
A function is a relation in which each x-coordinate corresponds to exactly one y-coordinate.
First, let's look at A.
{(1, 1), (4, 6), (4, 9)}
In the relation shown above, notice that the x-coordinate 4 appears twice. In one case, 4 corresponds to 6 and in the other case, 4 corresponds to 9. Since the x-coordinate 4 corresponds to more than one y-coordinate, this relation does not represent a function.
Now let's look at B.
{(2, 3), (2,5), (3,5)}
In the same way as the first relation we did, this relation is not a function since each x-coordinate does not have one unique y-coordinate. In one case, 2 corresponds with 3 and in the other, 2 corresponds to 5.
Since each x-coordinate does not correspond to exactly one y-coordinate, the relation shown here does not represent a function.
Now let's look at C.
{(3, 7), (5, 9), (7, 9)}
Notice that each of the x-coordinates shown above have only one unique y-coordinate. In other words, each x-coordinate is paired with a single y-coordinate and this is an example of a function.
Even though we have our answer, let's just look at D just to be sure.
{(4, 8), (4, 5), (6,3)}
Notice that 4 corresponds to 8 in one case and 5 in the other so this would not be an example of a function.
So, c will be your answer.
