To determine if line segment \( \overline{NO} \) is a constructed copy of line segment \( \overline{PQ} \), Thuy must check if the lengths of these two segments are the same. To do this, she should measure the distance of one segment and compare it with the other.
The correct response is:
She must measure the distance from point O to point Q using a compass and place the compass on point P to see if point N is the same distance.
This confirms that \( NO \) is the same length as \( PQ \).