Using a compass and a straightedge, a student constructed a triangle in which overline XY is one of the sides.

•----------------------------------------------•
X Y

The compass is opened to a set length and two intersecting arcs are drawn above overline XY using X and Y as centers. The intersection of the two arcs is labeled as point Z.

What could not be the length of the compass so that △XYZ is isosceles?
A. greater than XY
B. less than 1/2 XY
C. equal to XY
D. greater than 1/2 XY