To arrange the events chronologically, we need to know the year in which each occurred.
3) End of Emergency: The national emergency declared in 1975 by the Indira Gandhi government was officially lifted in March 1977.
4) Launch of Operation Barga: This was a major land reform movement in West Bengal, initiated by the Left Front government in 1978.
2) Implementation of Mandal Commission recommendations: The V. P. Singh government announced the implementation of the Mandal Commission's recommendations for reservations for OBCs in August 1990.
1) Economic liberalisation: The new economic policy of liberalisation, privatisation, and globalisation was introduced in India in 1991.
The correct chronological sequence is 1977 → 1978 → 1990 → 1991.
This corresponds to the order of events: 3, 4, 2, 1.