Answer asap! must be correct! more points!

A proportional relationship between two quantities is one in which the two quantities vary directly with one and other. If one item is doubled, the other, related item is also doubled.

So the answer would be C

But lets see the proof:
The first x and y ratio is 2:6 which equals 1:3
The second one is 4:12 which equals 1:3
The third one is 6: 18 which equals 1:3
The fourth one is 8: 24 which equals 1:3

Which means all 4 of the ratios are the same. So therefore the answer is C

A proportional relationship meaning that all the sets are proportional.

A) 2/6 = 0.33
     5/8 = 0.625

So, A is a wrong answer.

C) 8/4 = 2
    24/4 = 6

4/12 = 2/6
6/18 = 2/6

Therefore, we have a proportional relationship!

-  C.