To determine if \( \overline{NO} \) is a copy of \( \overline{PQ} \), Thuy needs to measure the distance between the endpoints of both segments. The correct method would involve comparing the lengths of \( \overline{PQ} \) and \( \overline{NO} \) by using a compass.
The correct response is:
She must measure the distance from point N to point O using a compass and place the compass on point P to see if point Q is the same distance.
This ensures that the lengths of both segments are identical, confirming that \( \overline{NO} \) is a constructed copy of \( \overline{PQ} \).