B is the answer because a proportional relationship has a point of (0,0) which is located at the origin but can still be found by working backwards.
A. Is wrong because it does not have a point of (0,0) but (0,1). We need (0,0).
D. Is wrong because it is false, when working backwards, we get (1,1) not (0,0).
And C is wrong as well for the same reason as A. 1-2 is NOT 0. 6-2 is NOT 0.
B is our last option and to check, working backwards, 5-5=0 and 1-1=0 perfect.
I hope that helps, if you have any questions, feel free to ask!!
