To find a line of reflection that flips the polygon onto itself, we first consider the coordinates of the vertices given:
- W (-n, 0)
- X (n, 0)
- U (?, -k)
- V (-m, -r)
Given that the polygon is plotted in quadrants 3 and 4, the most apparent line of reflection that produces symmetry across the vertical axis would be the y-axis (x = 0). However, the options provided suggest we need to think about specific values related to the coordinates of the vertices.
Among the options:
- x = -m - This line would reflect points around the vertical line through -m.
- x = n - This line would reflect points around the vertical line through n.
- y = 0 - This is the x-axis line; reflecting over this would not maintain the polygon's position in quadrants 3 and 4.
- y = -r - This is a horizontal line; depending on the value of r, but does not align with a typical axis of symmetry for the given coordinates.
Given that points W and X have symmetrical x-coordinates around the y-axis, and considering the standard symmetry in polygons, the best line of reflection for maximum symmetry would typically be the y-axis itself or a similar approach. However, we need to select from the provided options.
Since the question is looking for a line of reflection that maintains the vertices in quadrants 3 and 4 and leads to symmetry across the y-axis, the best option from the list provided would be:
y = 0
This choice reflects the polygon horizontally, maintaining a structure for reflection across the horizontal axis. Thus, the correct answer is:
y = 0.