At the Yalta Conference, the 'Big Three' decided to organise a United Nations Conference on the proposed world organisation. The 'Big Three' stood for:

Roosevelt, Churchill and Stalin

The correct answer is Option (2) → Roosevelt, Churchill and Stalin

At the Yalta Conference, 1945, the 'Big Three' stood for Roosevelt, Churchill and Stalin.

Origin of the United Nations:

The pivotal Yalta Conference in February 1945 saw Roosevelt, Churchill, and Stalin, the 'Big Three', agree to convene a conference to establish a formal international organization aimed at promoting peace and cooperation among nations. This vision took shape over the course of a two-month-long conference in San Francisco from April to May 1945, culminating in the signing of the United Nations Charter by representatives from 50 nations on June 26, 1945. Poland later joined on October 15, bringing the total founding members to 51. Finally, on October 24, 1945, the United Nations officially came into existence, marking a historic milestone in global diplomacy and cooperation. India, among the earliest to join, became a member on October 30, 1945, reflecting the UN's rapid expansion and universal appeal. Thus, the United Nations emerged as a beacon of hope amidst the chaos of war, embodying the collective aspirations of nations for a more peaceful and prosperous world.