In August of 1963, representatives of the United States, Soviet Union, and Great Britain all signed the "Limited Nuclear Test Ban Treaty." This treaty limited/prohibited the testing of nuclear weapons in outer space, underwater, or anywhere in the atmosphere.
He taught them his ideas of universal laws spread to common people.
The correct answer among all the other choice is D. U.S. naval blockade of Cuba. This event resulted in the greatest threat of nuclear war. Thank you for posting your question. I hope this answer helped you. Let me know if you need more help.