Which of the following statements explains why the set of ordered pairs does NOT define a function?

{(3,6), (4,8), (5,10), (3,1), (6,12), (7, 10)}

A
Some ordered pairs use x and y values of different signs.

B
Some ordered pairs use the same number for both the x and y values.

C
Some ordered pairs use the same x value with different y-values.

D
Some ordered pairs use the same y value with different x values.