Which of the following tables represents a proportional relationship?
A.
x 3 4 5 6
y 6 9 12 18


B.
x 3 6 9 12
y 9 18 27 36


C.
x 3 6 7 8
y 9 12 15 18


D.
x 3 6 9 15
y 9 18 27 36