Answer : 2. "San Francisco Conference"
Explanation :

The San Francisco Conference, also known as the United Nations Conference on International Organization, was held in 1945. During this conference, the final approval and adoption of the United Nations Charter occurred. Delegates from various countries gathered in San Francisco to establish the UN, and the charter, which serves as the foundational document of the organization, was signed on June 26, 1945. This marked a significant step in the post-World War II efforts to promote international cooperation, peace, and security.