Which Statement Best Describes the North Atlantic Treaty Organization (NATO)

Which statement best describes the North Atlantic Treaty Organization (NATO) ?

A) An organization of the United States and other Western European nations that cooperatively pursue their shared security interests.
B) An organization formed to promote free trade in North and South America.
C) An organization of the United States, Germany, Russia, Australia, and India formed to counteract the growing threat of China.
D) An organization of France, China, the Russian Federation (replacing the former Soviet Union) , the United Kingdom, and the United States to pursue joint economic interests.