To have a Proportionality equal to 1, you must have the same number in the numerator and denominator.
(D) y = x is your answer, because:
if y = 1, then x = 1, because of transitive property. And 1/1 = 1
if y = 2, then x = 2, because of transitive property. And 2/2 = 1
hope this helps
