the vertices of a triangle are P(4, 7), Q8, -1), and R(-9, 6). What are the vertices of the image reflected across the x-axis?
A. P(4, 7), Q'(8, -1), R'(-9, 6)
B. P'(-4, -7), Q'-8, 1), R'(9, -6)
C. P(-4, 7), Q'(-8, -1), R'(9, 6)
D. P'(4, -7), Q'8, 1), R'(-9, -6)