The principal organs of the United Nations include:
UNESCO (C) is a specialized agency, not a principal organ.
| LIST-I (International Events) | LIST-II (Year) |
|---|---|
| A. Hiroshima and Nagasaki atomic bomb attacks | III. $1945$ |
| B. Formation of WTO | IV. $1995$ |
| C. Soviet Invasion of Hungary | II. $1956$ |
| D. Collapse of the Soviet Union | I. $1991$ |
Match List-I with List-II 

