Final answer:
The set of transformations that has been performed on triangle ABC to form triangle A'B'C' is dilation by a scale factor of 4 followed by reflection about the x-axis.
Step-by-step explanation:
The set of transformations that has been performed on triangle ABC to form triangle A'B'C' is A. Dilation by a scale factor of 4 followed by reflection about the x-axis.
To form A'B'C', the triangle has been enlarged or dilated by a scale factor of 4, meaning that every side and angle of ABC has been multiplied by 4 to create A'B'C'. After the dilation, the triangle has been reflected about the x-axis, which means that every point on the triangle has been mirrored across the x-axis.