Which of the following is the purpose of the north Atlantic Treaty organization?

1 economic aid
2 open borders
3 see patrolling
4 common defense

The purpose of the North Atlantic Treaty Organization (NATO) is:

4. Common defense

NATO was established in 1949 for collective defense against aggression, primarily in response to the threat from the Soviet Union at the time. Its Article 5 stipulates that an attack against one member is considered an attack against all, allowing for a collective response. NATO's original intent was not focused on economic aid, open borders, or sea patrolling as primary objectives, although these elements might be involved in its activities to fulfill its defense mission.