To determine if segment \( NO \) is a constructed copy of segment \( PQ \), Thuy should measure the length of \( NO \) and compare it with the length of \( PQ \).
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 is appropriate because it explicitly mentions measuring \( NO \) and using the compass to check if \( PQ \) is the same length, which is essential for establishing that \( NO \) is a copy of \( PQ \).