For which set of lines is it reasonable to state that the two lines are almost perpendicular to each other? a) y = 2.1x + 3, y = 2.1x + 5 b) y = 0.9x + 5, y = -1.26x + 8 c) y = 5x + 1.25, y = -5x + 1.25 d) y = 3 4 x + 0.28, y = 4 3 x + 0.29