Concept:The United Nations was founded after World War II to prevent future wars. Its Charter came into force on 24 October 1945, officially establishing the organisation.
Explanation:On 25 April 1945, 50 countries met in San Francisco to draft the UN Charter.
The Charter was adopted on 25 June 1945.
It took effect on 24 October 1945 after enough members ratified it.
This date is celebrated as United Nations Day.
The UN replaced the ineffective League of Nations.
Its main goals are maintaining peace, developing friendly relations, and promoting human rights.
Thus, the United Nations Organisation was established on 24 October 1945.
Answer:A. 24 October, 1945