Two lines are perpendicular if their slopes multiply to -1. That means we have to look at each individual answer and see if the slopes multiply to -1.
y = 2x - 1 has a slope of 2
2y = -x + 3
y = -1/2x + 3 This has a slope of -1/2.
2 * -1/2 = -1.
Since the slopes of these lines multiply to -1, the answer is A. Since we have our answer, we don't have to do anything else.
