The Mandal Commission recommended the reservation for

Other Backward classes

The correct answer is option (3) - Other Backward classes

The Mandal Commission was formed on 1 January 1979.
The Mandal Commission, officially known as the "Second Backward Classes Commission," was formed in India to address the issue of social and educational backwardness among various communities.
In August 1990, the National Front government decided to implement one of the recommendations of the Mandal Commission pertaining to reservations for OBCs (Other Backward classes) in jobs in the central government and its undertakings. This decision sparked agitations and violent protests in many cities in north India.