What is the mirror image of point(3,9) on x-axis

What is the mirror image of point(3,9) on x-axis is
a)(-3,9)
b)(9,3)
c)(3,9)
d)(3,-9)

The mirror image of the point (x, y) in the x-axis is the point (x, -y).
Thus, the mirror image of (3, 9) in x-axis is (3, -9).