Concept:
The Second Backward Classes Commission, popularly known as the Mandal Commission , was appointed by the Janata Party government in December 1978 under the chairmanship of B.P. Mandal. Its objective was to investigate the conditions of socially and educationally backward classes in India and recommend measures for their advancement.
• Key Recommendation: The Commission submitted its detailed report in December 1980, identifying $3,743$ castes as backward and recommending a $27\%$ reservation in central government jobs and educational institutions for Other Backward Classes (OBCs).
• Implementation: The recommendations lay dormant during the Congress governments led by Prime Ministers Indira Gandhi and Rajiv Gandhi throughout the 1980s until political realignments occurred in late 1989.
Step 1: Contextualizing the formation of the National Front Government.
In the Ninth Lok Sabha elections held in November 1989, no single political party won a clear majority. The Janata Dal, led by Vishwanath Pratap Singh (V.P. Singh), coalesced with several regional parties to form a coalition government known as the National Front (Rashtriya Morcha). The National Front government was supported from the outside by two ideologically opposite political blocs: the Bharatiya Janata Party (BJP) and the Left Front.
Step 2: Decision to implement the Mandal Commission Report.
In line with its electoral manifesto promises to empower backward communities and deepen social justice, Prime Minister V.P. Singh announced in Parliament on $7^{\text{th}}$ August 1990 that the National Front government had decided to implement the Mandal Commission recommendation of reserving $27\%$ of Central Government jobs for candidates belonging to the Other Backward Classes (OBCs).
Step 3: Examining the options.
• Option (A) Indian National Congress: Did not implement the report during its tenure from 1980 to 1989; later introduced $27\%$ reservation in higher educational institutions in 2006 under the UPA rule, but the historical decision of initial implementation in 1990 was made by the National Front.
• Option (B) National Front: Correct. Led by Prime Minister V.P. Singh in August 1990.
• Option (C) United Front: A multi-party coalition that ruled India between 1996 and 1998 under H.D. Deve Gowda and I.K. Gujral, formed long after the Mandal decision was already implemented.
• Option (D) Janata Party: Appointed the Mandal Commission in 1978 under Morarji Desai, but collapsed in 1979 before the report was submitted in 1980.
Step 4: Final conclusion.
Therefore, the political alliance responsible for deciding to implement the Mandal Commission recommendations was the National Front .