Answer:
y = x line
x = 0 line
Explanation:
The polygon ABCD showed in the image attached is first reflected across the y = x line, from the second quadrant to the fourth quadrant. This reflection will result like the second image.
Then, it's reflect across the y-axis, which in terms of lines would be x = 0 line. This reflection will be like the last position showed in the first image, it's a common reflection with y-axis as a mirror.