Which table shows a proportional relationship between x and y?
a. x 8 12 14 16
y 2 3 4 5

b. x 3 4.5 8 12
y 2 3 4 8

c. x 1 4 5 10
y 15 60 70 120

d. x 1 2 5 7
y 5 10 25 35

need ! answer !