answer:
D. y = 3x + 9
perpendicular means negative reciprocal of the number next to x
so if its 5x perpendicular would be -1/5x
make the equation look like y = ...
2x + 6y = 6
6y = -2x + 6
y = (-2x + 6)/6
y = -2x/6 + 6/6
y = -1/3x + 1
perpendicular line would be a negative reciprocal so
-1/3x would have a perpendicular that would be 3x
D. is the only one that has 3x