Which table shows a proportional relationship between x and y?

X: 1 2 7 8
Y: 0.5 1 3.5 4


X: 3 7.5 15 20
Y: 1 2.5 4 6


X: 2 3 4 5
Y: 7 9 11 13


X: 3 6 8 10
Y: 12 15 18 20