The pair of lines that are perpendicular is: D) x + y = 10; x - y = 3.
We can determine this by rearranging each equation into slope-intercept form (y = mx + b), where m is the slope of the line. The slopes of two perpendicular lines are negative reciprocals of each other.
For the first equation, we have:
x + y = 10
y = -x + 10
So, the slope of the first line is -1.
For the second equation, we have:
x - y = 3
y = x - 3
So, the slope of the second line is 1.