Final answer:
NATO is a military alliance of European and North American democracies aimed at ensuring mutual security and defense, with an attack on one member being an attack on all.
Step-by-step explanation:
The North Atlantic Treaty Organization (NATO) is a military alliance that includes the United States, Canada, and various European nations. Founded after World War II, NATO's primary objective is to ensure the security and defense of its member countries against external threats. Initially, NATO focused on deterring Soviet aggression during the Cold War, and over time, it has expanded to include countries from Eastern Europe as well. The key principles of NATO involve collective defense, meaning an attack on one member is considered an attack on all, thereby offering a structure for mutual military assistance among member states.
Therefore, the correct answer regarding what NATO represents is option (b) It is a military alliance of European and North American democracies founded after World War II to strengthen relations between member states.