Which table represents a linear function?
x 1 2 3 4 5
y 5 10 15 20 25

x 1 2 3 4 5
y 5 20 45 80 125

x 1 2 3 4 5
y 5 25 125 625 3,125

x 1 2 3 4 5
y 2 4 8 16 32