The answer is A. A perpendicular equation will have the opposite and reciprocal slope as the original equation.
Once converted to the slope-intercept form of y = mx+b, we find the two equations for A are y = 2x-1 and y = (-1/2)x + 3/2. The opposite reciprocal of the first equation's slope (m in the equation form given) is -1/2, which as you can see if the slope of the other equation.
