The answer is B.
In order for this chart to be true, each x and y pair must be proportional to the other ones. (in other words, each row of x and y should increase the same amount as the other ones.)
look at the first row. we can write this as 3/5 (x over y). then look at the third and fourth row. 6/10 = 3/5, and 9/15 = 3/5, so the pairs are proportional.