Triangle ABC is graphed on a coordinate plane with vertices at A (-3,7), B (9,-8), and C(-5,-6). If triangle ABC is dilated by a scale factor of m with the origin as the center of dilation to create triangle A'B'C', what will be the coordinates of the dilated vertex B? (9+m, -8m) (9m, 8m) (9+m, 8+m) (9m, -8m) ​