Select the pair of equations whose graphs are perpendicular.

A.) 5x - 8y = 9
12x - 5y = 7

B.) 3x + 6y = 8
y = 3x - 8

C.) y = 2x - 7
x + 3y = 3

D.) 2y = -3x + 5
2x - 3y = 4