A four-sided figure WXYZ is shown on the coordinate plane. The figure is then reflected across the y -axis. Which point of the figure above will end up in Quadrant I?
Since the reflection is across the y-axis, the x-coordinate of each point will be negated while the y-coordinate remains the same. The point labeled W is located in Quadrant II, because it has positive y-coordinate and negative x-coordinate. After reflection, the x-coordinate of point W becomes positive and the y-coordinate remains positive, so the reflected point W' will end up in Quadrant I. Answer: \[\boxed{\text{W}}.\] [asy]
unitsize(0.5 cm);
pair W, X, Y, Z;
W = (-5,2);
X = (-2,-1);
Y = (-1,3);
Z = (4,1);
draw((-6,0)--(6,0));
draw((0,-2)--(0,5));
draw((0,0)--W--X--Y--Z--cycle);
label("$W$", W, NW);
label("$X$", X, S);
label("$Y$", Y, N);
label("$Z$", Z, NE);
[/asy]