Answer:
The correct option is 1. The image of (2,4) is (4,-8).
Step-by-step explanation:
The given rule is

The transformations perform from right to left.
means dilation with scale factor 2 and center of dilation is origin.
The given rule defines the dilation with scale factor 2 and center of dilation is origin followed by reflection across x-axis.
If a figure dilated by scale factor k and the center of dilation is origin, then

The scale factor is 2,


If a figure reflected across x-axis, then x-coordinate remains the same but the sign of y-coordinate is changed.


Therefore image of (2,4) is (4,-8) and option 1 is correct.