The x-coordinates of the two points are the same, so they lie on the same vertical line.
They lie on the opposite sides of the x-axis, so you must add the distance from one point to the x-axis to the distance from the other point to the x-axis.
The distance from the point (8,3) to the x-axis is 3.
The distance from the point (8,-6) to the x-axis is 6.
3+6=9
The answer is C. 9 units.
