To find the reflection of point A (-7, -8) across an axis that results in point B (7, 8), we can observe that the x-coordinates of the two points have opposite signs, and the y-coordinates of the two points also have opposite signs. This suggests that point B is a reflection of point A across both the x-axis and the y-axis.
However, reflecting a point across the x-axis and then the y-axis is equivalent to reflecting the point across the origin. Therefore, point B is a reflection of point A across the origin.
So the correct option is:
C. The x-axis and then the y-axis