To determine if \( \overline{NO} \) is a constructed copy of \( \overline{PQ} \), Thuy needs to show that the lengths of the segments are the same. The most appropriate method would involve comparing the lengths of the segments.
Among the options provided, 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 option allows Thuy to directly compare the lengths of the two segments \( \overline{NO} \) and \( \overline{PQ} \) to establish that they are indeed copies of each other.