A way to remember if a pair of lines are perpendicular or not is by looking at the two slopes of the equation. In both of those equations, we see that 3/2 and -2/3 are negative reciprocals. Perpendicular slopes are always negative reciprocals meaning that only answer C is the correct one.
this is because perpendicular lines have the opposite reciprocal slopes. So, 3/2 is the opposite reciprocal of -2/3 since it is negative and that is the opposite sign. Then, it is the reciprocal of the fraction since the numerator and the denominator are switched. If you check the other answer options, you will see that none of the slopes are the exact opposite reciprocal.
