I believe the answer is the second option.
When man learned to write, to use metals, and to work with others we say he became "civilized", although the exact parameters of civilization vary in interpretation.
Explanation:
The release of two atomic bombs on Japan in August 1945 helped end World War II but ushered in the Cold War, a conflict between the United States and the Soviet Union that dragged on nearly half a century. ... Cold War calculations led to a divided Germany and U.S. involvement in wars in Korea and Vietnam