The answer should be A. For example, if x = 1, and the ratio between x and y is y is 5 times greater than x, then y would equal 5, which is only true in A.
Or, use the number 5 as an example. If x = 5, and the ratio between x and y is y is 5 times greater than x, then y is 5.
And if you put that into A, y = 5x, it becomes 25 = 5(5)
Then 25 = 25, which is true!