Place the compass on the endpoint of the segment. Option C
How do you copy a segment?
Placing the compass on the endpoint of the segment to be copied or bisected is a common step in using a compass. The first step is to place the compass at one of the segment's endpoints, whether you are splitting or duplicating a segment.
The next steps are different: in copying, you use the compass to extend a ray, and in bisecting, you draw arcs on both sides of the segment to find its midpoint. Notwithstanding these differences, the compass is first placed at the endpoint in both procedures.