Which of the following tables represents a proportional relationship?

A.
x
12
18
30
36
y
10
15
25
30


B.
x
8
12
16
24
y
10
15
25
30


C.
x
12
18
30
36
y
4
8
16
24


D.
x
12
18
30
36
y
12
24
36
48