math
posted by morgan .
which of the following is an example of a proportional relationship between x and y?
A. y = 2
B. y = 3x
C. 4y + 4x = 6
D. 4y  2 = 2x  4

I couldn't even understand the question, can anyone help?

http://www.mathsisfun.com/algebra/crossmultiply.html
The only choice that has y on one side and x on the other is D. 
so when the quetion comes like this, x and y are impossible in one side together? but B also is y on one side and x on the other side, i am so confused.